C# Interop.Excel can't find dll

this ist my first VS and C# project. I want to access an excel file and add some data. Pretty much standard I guess. So I used a code example from the microsoft page (see below). No red underlines in the editor. But when I run it, I get the error message below. I guess it is not a problem of the code. Can anyone help me or send me a helpful link?

I use Visual Studio 2019 Community and Office 365 64-bit.

Error: Message=Unable to cast COM object of type 'Microsoft.Office.Interop.Excel.ApplicationClass' to interface type 'Microsoft.Office.Interop.Excel._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D5-0000-0000-C000-000000000046}' failed due to the following error: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY))

I already tried this solution, but it didn't work.

VB: Error loading type library/DLL. (Exception from HRESULT: 0x80029C4A (TYPE_E_CANTLOADLIBRARY)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel;
using System.Reflection;

namespace test2Excel
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, System.EventArgs e)
        {
            Excel.Application oXL;
            Excel._Workbook oWB;
            Excel._Worksheet oSheet;
            Excel.Range oRng;

            try
            {
                //Start Excel and get Application object.
                oXL = new Excel.Application();
                oXL.Visible = true;

                //Get a new workbook.
                oWB = (Excel._Workbook)(oXL.Workbooks.Add(Missing.Value));
                oSheet = (Excel._Worksheet)oWB.ActiveSheet;

                //Add table headers going cell by cell.
                oSheet.Cells[1, 1] = "First Name";
                oSheet.Cells[1, 2] = "Last Name";
                oSheet.Cells[1, 3] = "Full Name";
                oSheet.Cells[1, 4] = "Salary";

                //Format A1:D1 as bold, vertical alignment = center.
                oSheet.get_Range("A1", "D1").Font.Bold = true;
                oSheet.get_Range("A1", "D1").VerticalAlignment =
                Excel.XlVAlign.xlVAlignCenter;

                // Create an array to multiple values at once.
                string[,] saNames = new string[5, 2];

                saNames[0, 0] = "John";
                saNames[0, 1] = "Smith";
                saNames[1, 0] = "Tom";
                saNames[1, 1] = "Brown";
                saNames[2, 0] = "Sue";
                saNames[2, 1] = "Thomas";
                saNames[3, 0] = "Jane";
                saNames[3, 1] = "Jones";
                saNames[4, 0] = "Adam";
                saNames[4, 1] = "Johnson";

                //Fill A2:B6 with an array of values (First and Last Names).
                oSheet.get_Range("A2", "B6").Value2 = saNames;

                //Fill C2:C6 with a relative formula (=A2 & " " & B2).
                oRng = oSheet.get_Range("C2", "C6");
                oRng.Formula = "=A2 & \" \" & B2";

                //Fill D2:D6 with a formula(=RAND()*100000) and apply format.
                oRng = oSheet.get_Range("D2", "D6");
                oRng.Formula = "=RAND()*100000";
                oRng.NumberFormat = "$0.00";

                //AutoFit columns A:D.
                oRng = oSheet.get_Range("A1", "D1");
                oRng.EntireColumn.AutoFit();

                //Manipulate a variable number of columns for Quarterly Sales Data.
                DisplayQuarterlySales(oSheet);

                //Make sure Excel is visible and give the user control
                //of Microsoft Excel's lifetime.
                oXL.Visible = true;
                oXL.UserControl = true;
            }
            catch (Exception theException)
            {
                String errorMessage;
                errorMessage = "Error: ";
                errorMessage = String.Concat(errorMessage, theException.Message);
                errorMessage = String.Concat(errorMessage, " Line: ");
                errorMessage = String.Concat(errorMessage, theException.Source);

                MessageBox.Show(errorMessage, "Error");
            }
        }

        private void DisplayQuarterlySales(Excel._Worksheet oWS)
        {
            Excel._Workbook oWB;
            Excel.Series oSeries;
            Excel.Range oResizeRange;
            Excel._Chart oChart;
            String sMsg;
            int iNumQtrs;

            //Determine how many quarters to display data for.
            for (iNumQtrs = 4; iNumQtrs >= 2; iNumQtrs--)
            {
                sMsg = "Enter sales data for ";
                sMsg = String.Concat(sMsg, iNumQtrs);
                sMsg = String.Concat(sMsg, " quarter(s)?");

                DialogResult iRet = MessageBox.Show(sMsg, "Quarterly Sales?",
                MessageBoxButtons.YesNo);
                if (iRet == DialogResult.Yes)
                    break;
            }

            sMsg = "Displaying data for ";
            sMsg = String.Concat(sMsg, iNumQtrs);
            sMsg = String.Concat(sMsg, " quarter(s).");

            MessageBox.Show(sMsg, "Quarterly Sales");

            //Starting at E1, fill headers for the number of columns selected.
            oResizeRange = oWS.get_Range("E1", "E1").get_Resize(Missing.Value, iNumQtrs);
            oResizeRange.Formula = "=\"Q\" & COLUMN()-4 & CHAR(10) & \"Sales\"";

            //Change the Orientation and WrapText properties for the headers.
            oResizeRange.Orientation = 38;
            oResizeRange.WrapText = true;

            //Fill the interior color of the headers.
            oResizeRange.Interior.ColorIndex = 36;

            //Fill the columns with a formula and apply a number format.
            oResizeRange = oWS.get_Range("E2", "E6").get_Resize(Missing.Value, iNumQtrs);
            oResizeRange.Formula = "=RAND()*100";
            oResizeRange.NumberFormat = "$0.00";

            //Apply borders to the Sales data and headers.
            oResizeRange = oWS.get_Range("E1", "E6").get_Resize(Missing.Value, iNumQtrs);
            oResizeRange.Borders.Weight = Excel.XlBorderWeight.xlThin;

            //Add a Totals formula for the sales data and apply a border.
            oResizeRange = oWS.get_Range("E8", "E8").get_Resize(Missing.Value, iNumQtrs);
            oResizeRange.Formula = "=SUM(E2:E6)";
            oResizeRange.Borders.get_Item(Excel.XlBordersIndex.xlEdgeBottom).LineStyle
            = Excel.XlLineStyle.xlDouble;
            oResizeRange.Borders.get_Item(Excel.XlBordersIndex.xlEdgeBottom).Weight
            = Excel.XlBorderWeight.xlThick;

            //Add a Chart for the selected data.
            oWB = (Excel._Workbook)oWS.Parent;
            oChart = (Excel._Chart)oWB.Charts.Add(Missing.Value, Missing.Value,
            Missing.Value, Missing.Value);

            //Use the ChartWizard to create a new chart from the selected data.
            oResizeRange = oWS.get_Range("E2:E6", Missing.Value).get_Resize(
            Missing.Value, iNumQtrs);
            oChart.ChartWizard(oResizeRange, Excel.XlChartType.xl3DColumn, Missing.Value,
            Excel.XlRowCol.xlColumns, Missing.Value, Missing.Value, Missing.Value,
            Missing.Value, Missing.Value, Missing.Value, Missing.Value);
            oSeries = (Excel.Series)oChart.SeriesCollection(1);
            oSeries.XValues = oWS.get_Range("A2", "A6");
            for (int iRet = 1; iRet <= iNumQtrs; iRet++)
            {
                oSeries = (Excel.Series)oChart.SeriesCollection(iRet);
                String seriesName;
                seriesName = "=\"Q";
                seriesName = String.Concat(seriesName, iRet);
                seriesName = String.Concat(seriesName, "\"");
                oSeries.Name = seriesName;
            }

            oChart.Location(Excel.XlChartLocation.xlLocationAsObject, oWS.Name);

            //Move the chart so as not to cover your data.
            oResizeRange = (Excel.Range)oWS.Rows.get_Item(10, Missing.Value);
            oWS.Shapes.Item("Chart 1").Top = (float)(double)oResizeRange.Top;
            oResizeRange = (Excel.Range)oWS.Columns.get_Item(2, Missing.Value);
            oWS.Shapes.Item("Chart 1").Left = (float)(double)oResizeRange.Left;
        }
    }
}

Interop always requires MS Office installed on your PC.

Looks like you are using Office 365 on web.

Anyways, the library excellibrary , can help

https://code.google.com/archive/p/excellibrary/

The Other option is using npoi NuGet which is a .NET library that can read/write Office formats without Microsoft Office installed. No COM+, no interop.

https://github.com/nissl-lab/npoi

https://www.nuget.org/packages/NPOI/