It's not just you, there is indeed an activation problem in Microsoft 365 Office triggered by administrators making changes at the licensing level.… The problem has been ongoing for a few months ...
Open Microsoft 365, then click the account icon in the upper, right-hand corner. Select My Account, then Manage Installs. From there, you can de-activate an installation if you are at your limit of 5 ...
The latest version of Microsoft ... do not attempt to install the 64-bit Office version on a 32-bit Windows. If prompted for a product key or to sign in after you've installed Office, click Sign in to ...