Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
You may have to uninstall all Office products using the Uninstall support tool (see Option 2 in the article at https://support.microsoft.com/en-us/office/uninstall-office-from-a-pc-9dd49b83-264a-477a-8fcc-2fdf5dbf61d8) and then start fresh.