Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
The link refers to pop ups about Office 13 to Office 16 upgrades. It refers to changing the registry. Registries are found on Windows computers. If a Mac has an equivalent to a registry it calls it something else.
The pop-up I see is new since I updated to the latest version of Office 365 on my Mac. Screen shot below.