Hey amy247 ,
it sounds like this meeting was organized by a Teams for work or school user. You have two options to join this meeting without using your corporate account:
1) Sign out of your corporate account and use that Teams app to join the meeting as a guest. You can select your display name and your corporate account identity is not shown to the meeting participants. This could be the preferred option as joining the meeting in the app gives you the best meeting experience.
2) Join the meeting as a guest in browser. Similarly, you can select your display name and your corporate account identity is not shown to the meeting participants. This is a simple option with a good meeting experience and no need to sign out of your corporate account.
The Teams free app on Windows 11 used with your personal login does not yet support meetings organized by Teams for work or school users.
Hope this helps!
Miikka (Teams PM)