Hello Coos,
[Topic moved here.]
A forum search for "Windows 11" finds some feedback from a few Hauptwerk users who are using it successfully, e.g.:
viewtopic.php?f=16&t=19979#p149847
viewtopic.php?f=16&t=20099&p=151411#p151411
viewtopic.php?f=16&t=19986&p=151522#p151522
viewtopic.php?f=16&t=20147&p=152755#p152755
Windows 11 is still relatively immature, and if considering it it would certainly be worth making sure drivers for your hardware are available from its manufacturers and listed as supported on it.