Apple switched to a new version of the Apple Mobile Device Service for these newer apps on Windows, which are not compatible with AltStore at this time. Just so people don't waste their time cough like me cough trying and failing to get it to work without following the guide to the letter with the no-longer-supported iTunes.
Maybe put in a note saying 'use a different PC or VM' to get around it. I didn't want to uninstall Apple Music or Apple Devices just for this.