Groups within Teams Free for shared interests, collaboration, and communication
This issue typically occurs when the Microsoft Teams account you're signed into does not match the email address that received the community invitation, or the invitation link has expired. Try signing out of Teams and signing back in with the same email address that received the Gmail invitation, then open the link again. If the community still does not appear, ask the community owner to generate and send a new invitation link, as the original link may no longer be valid or may have already been used.