Not able to download M2RET to Macchina M2 for SavvyCAN

Hi! I am trying to get my Macchina M2 working with SavvyCAN on a Windows 11 PC. The M2 Docs page says to download M2RET and use a batch file to flash it to the M2. The M2 Docs has a broken link to M2RET, but I was able to find it myself on the SavvyCAN homepage. I know my USB connection is good because Windows recognizes the M2 and assigns a COM port. However, when I run the M2RET batch file, it just says “Device COM X is not available” for each COM port, it never says it connects with the M2 or downloads the flash contents. So when I try to open a connection in SavvyCAN, no CANBus data comes through.

Is there something special I need to do to reflash the M2 with M2RET on Windows 11? Is there an alternative to SavvyCAN that is known to be working that I can use instead?