Using Outlook for Android in business environments for email and scheduling
Microsoft, shame on you! I tried all the suggestions listed here and the only one that worked was hinted at in an earlier reply: try logging in using the Edge browser. That's right, no other browser would let me log in, only Edge. Nothing else about my account or system changed in the meantime, and no time had passed since my other attempts. If MS is going to force us to use their browser to log in, the least they could do is give us a meaningful error message that tells us so.