Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello,
To run Microsoft Office applications, your Mac should be running macOS 12 or later. If you are using an older version of macOS, unfortunately, there is no supported way to bypass this requirement and continue running the Office applications.
In this situation, your options are to upgrade your Mac to a supported macOS version (Mac OS 12 or above if possible) or to consider upgrading the device itself.
Since Microsoft recently updated its licensing certificates, even older versions of Microsoft 365/Office applications that were previously compatible with your macOS version may no longer work.
If upgrading macOS or your device is not possible, you may need to cancel your Microsoft 365 Premium subscription and request a refund.
For reference, see: