Cannot be added to TEAMS CHANNELS

Dear @Flávia Silva,

Thank you for reaching out to Microsoft Q&A forum.

I’m sorry to hear about the issue you’re experiencing with Teams. I understand you’re having difficulty accessing Teams channels after being added. The error message you provided indicates a common configuration conflict in Microsoft 365, typically related to External Access or Guest Access settings.

The error message you show suggests that your account is currently being treated as an external user trying to access a Team/Channel owned by an organization tenant. The user account you are signing in with has not been properly provisioned or fully accepted into the organization's directory (Azure AD).

This issue cannot be fixed by you or the channel organizer; it requires the Administrator of the target organization to take specific steps in their system.

The organizer's attempts to add you to the Team may be failing because your account needs to be explicitly invited and accepted at the organization level first.

• The administrator needs to go to the Azure Active Directory (Azure AD) portal and manually invite your email address as a Guest User into their organization.
• Once the admin sends this explicit invitation, you must look for the invitation email from Microsoft and click the link to accept the invitation. This final step provisions your guest account.

The admin may need to ensure their organization's overall settings are not blocking external access.

• Action for Admin: Check the Teams Admin Center or SharePoint Admin Center to ensure Guest Access is fully enabled for their organization and for that specific Team/Channel.

Please forward this error message directly to the IT Administrator of the organization you are trying to access. They are the only party with the permissions to resolve this external user access issue. If you do not know who the IT administrator is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support 
For reference: Add, invite guest external users to your organization - Azure DevOps Services | Microsoft Learn

I truly hope you get your issue resolved swiftly. Please know that even though I can't directly intervene, directing you to the correct, specialized support is the most effective help I can provide from my position. Thank you for your patience and understanding. I'm looking forward to your reply.  

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".  

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.