Information about save file from the server in user PC

I have an asp.net mvc project (intranet) and have a page that export an excel.

I do it with an interop excel and I want to know how can I save this excel file inside a default folder on user PC, my project is on my Server PC.

When I try to open the excel after created it with interop (oXL.visible = true) it open on Server PC.

I tryed with this Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) but i got this error:

Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed due to the following error: 8000401a The server process could not be started because the configured identity is incorrect. Check the username and password. (Exception from HRESULT: 0x8000401A).

I want to know too, if I try like this link: Retrieving the COM class factory for component with CLSID {00024500-0000-0000-C000-000000000046} failed while configure exe in task scheduler
my problem will be resolved?

Im accept another way to create an excel file, but need to be free to commercial user