Well, the install completed and I've installed all her software. But we then got yet ANOTHER notice that there was "a problem with her Microsoft account" -- and guess what, the password we just used to log in is no longer the correct password. But when I get the code to change passwords, and enter that exact same password again, it tells us we "can't use a previously used password." So it's both WRONG and RIGHT at the same time.
Changed it for the fourth time. Fingers crossed that this one sticks.