Looking at the root cause report, I can tell you that it has not been widely reported, so it’s not a common issue. Can you share the .kmp file with us (via DM on the forum is fine)?
One question: where is the .kmp file stored? Is it somewhere that might not be accessible to the Administrator account which needs to access it during the install process?
@Marc, you got it - the location seemed to be causing the problem. Copying it to the C:\Users…\Documents folder and installing it from there worked just as expected.
More info: I am running Keyman for Windows under Parallels on an M1 Mac. It was in a folder on the hard drive that Windows has write permission to but is finally ‘really’ in macOS, mapped as a network drive with a drive letter.