Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Are you subscribed to a Microsoft 365 subscription?
Using the Microsoft account used for the purchase, see if your license is active: https://account.microsoft.com/services/
Open Excel, click your profile picture, then hit Log out. Then restart your Mac computer.
Log back in to your account with the license and see if your subscription is now recognized.