Hello @Arthur Young
Welcome to Microsoft QnA!
Have you done carefully this process ?
https://learn.microsoft.com/en-us/microsoft-copilot-studio/publication-add-bot-to-microsoft-teams
You need to add the CoPilot in the Organization and approve it !
Please go through this step by step !
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I hope this helps!
Kindly mark the answer as Accepted and Upvote in case it helped!
Regards