Hello Ini Nkanga,
Good day! Thanks for posting in the Microsoft Community. We are happy to assist you.
The error message you received indicates that the Project may not be enabled for your organization. To use Project in Teams, you will need to ensure that it is enabled for your Office 365 account. You can contact your Office 365 admin to enable Project for your organization. Once Project is enabled, you should be able to add it to a channel in Teams without any issues.
If you are the admin follow these steps: log in to Microsoft Teams Admin Center> Tams apps > Manage Apps > search for Project and check app status. If the status is blocked click on the app and at the top right-hand side select actions and unblock.
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We look forward to hearing from you! Thank you for your time. Have a good day!
Sincerely
Simbarashe | Community Moderator