Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
You experience is something new. I have not seen anyone else mention this problem.
OOPS!
I checked and it said I was running 2016 Pro Plus. That is not supposed to happen. I did have 2016 Pro Plus installed, but I moved it before I installed 365, so it should not be finding that program code or license. But it is, or it thinks it is. This makes me a bad test case
The theory, and practice I've been working under is that Office/Microsoft 365 installs a desktop copy. We can use it without signing in for up to 30 days. It will be mostly functional
Doing an Office Repair of 365 did not help.
But signing in did fix my problem.
This is not the way it is supposed to work ...