I was recently trying to set up a copy of the Outlook desktop app with two outlook.com email accounts and hit a strange issue.

I was able to add the first one without any problems, but when I tried to add the second one I got an error message asking for PIN, and most importantly on the same dialog showing the second outlook.com email address.

This is confusing as I know of no way to set a PIN on an outlook.com account.

Turns out it is just a badly designed dialog. It wants the PIN of the currently logged-in user on the Windows PC (made worse in my case as the PIN was not what I thought it was and had to be reset)

Once I had a working PIN for the local user login and entered it when prompted all was OK