I have a Matrix Portal M4, and I can run CircuitPython code on it just fine.
I cannot, however, get ANY Arduino code to run on it. I have all of the correct libraries imported into my Arduino console, and I can choose Matrix Portal M4 as the current board, but the PORT item in the menu is always ghosted. I run a newer build of Windows 10.
Do I need to use that Zadig utility to install a different driver? If you have a working system, which drivers are you using?