Additional features, settings, or issues not covered by specific Microsoft Teams categories
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Are you able to log in via Teams web with the same account?
The error message you provided indicates that access to the target Microsoft 365 tenant is being blocked by a Cross-Tenant Access Policy configured in Microsoft Entra ID.
If you are a regular user:
Please contact your IT Administrator, as this issue cannot be resolved from the client side. The administrator will need to review your organization's cross-tenant access settings.
If you are an IT Administrator:
Please review the following configuration in the Microsoft Entra Admin Center > External Identities > Cross-tenant access settings > Organizational settings
Verify that:
The target tenant is not blocked.
Outbound access is configured to Allow for the target tenant.
Any applicable B2B Collaboration or B2B Direct Connect settings permit access to the external organization.
I look forward for your response.