SSIS Multiple File Load Error with Variable

I have an SSIS package that is to load multiple Excel files using the For Each Loop Containter. As soon as I add the variable in the Excel Connection manager in expressions, under ExcelFilePath Property it throws an error in the Excel Source Package:

An OLEDB error has occurred 0X80004005. The MIcrosoft Access Database Engine cannot write to the file "C:..."

It is already opened exclusively by another user or you need permission. I had to already download the 32bit Extension to be able to view the Excel files. I've followed many guides on how to do this, and it always ends up in the same result. Delay validations are set to True. Any idea how to fix?