Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Yes, I did. Please read my first post again (home use program = HUP).
However, I tried now to install office using the installation link which I received with the key (resp. I requested a new link using my purchasing history). Also there I have to log in with a MS account before I can start the installation.
So far the only useful guide from MS was for uninstalling office on a mac. As mentioned, I'm done with office for mac. It seems that for MS mac users are way less important than windows users. :(