Hi @IBN
Please check if you have enabled these settings in Teams admin center:
1) Check if you have allowed all apps for custom apps. In the left navigation of the Microsoft Teams admin center, go to Teams apps > Permission policies>Add. Under Microsoft apps, Third-party apps, and Custom apps, select Allow all apps.
2)Check if you enabled the org-wide custom app settings. In the left navigation of the Microsoft Teams admin center, go to Teams apps > Manage apps. Click Org-wide app settings. Under Custom apps, turn on Allow interaction with custom apps
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