Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
There are some ongoing issues with the Office apps on an Apple Mac device at the moment, Office Professional Plus is a Windows only licence, if that is showing on your Mac, the Office licence may be corrupt.
Close all Office apps, then use the steps on this link to remove the Office licence from your Mac.
Then open an Office app and log into it with your Microsoft account to check if that resolves the problem.
If not, the best option is to uninstall the Office apps using the steps on this link, then download and reinstall Office form your Microsoft account online (https://account.microsoft.com/services/)
https://support.microsoft.com/en-us/office/lifecycle/officeinstall/uninstall-office-for-mac