Demonstrates reading XLSX file in PowerShell and using the data to create a KML file.
Depending on how you download the files you may need to unblock the DLLs: https://blogs.msdn.microsoft.com/delay/p/unblockingdownloadedfile/
You may also need to adjust the execution policy in order to be able to run Powershell scripts on your machine. As administrator:
set-executionpolicy RemoteSigned
If you don't have administrator rights, you can run the script with
powershell.exe -ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile -WindowStyle Hidden -File <script_name>