Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
You may have to remove your Office installation using the Uninstall support tool (see for example 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 with a reinstall.