Using New Outlook on Windows for professional communication and productivity
An M365 Personal account should be sufficient. Do you get this prompt at any time during this Add Account process?
If so, be sure to select Personal. The other thing to do is open a support ticket by clicking the Support Icon. A pane will open on the right where you can send them the info you posted.
You'll get a ticket number, please post it here once you get it; the support folks I've reported this issue to would like to track it from their side as well. Thanks!!