If you setup your MFA from a cell phone (maybe with the Outlook app) it did not create an app password for you. You will need to create one to be used for your email app and/or Outlook on the desktop.
Outlook on the desktop will NOT work properly without an app password.
To create/manage MFA app password(s), use this link or use the instructions below.
- Login to Office365.
- Click on your initial/picture at the upper right corner.
- Click My Account.
- Click Manage security and Privacy.
- Click Additional Security Verification.
- Click Create and manage app passwords.
- Click Create. Enter a name as prompted (the name isn't important).
- The system will then create and show you the app password. Note that this WILL NOT BE SHOWN AGAIN, so copy it and put it in a safe place.
- Use the new app password for the mail app on your phone and Outlook on the desktop.