Error Code:

Error Code	50178
Message	User account '{user}' from identity provider '{idp}' does not exist in tenant '{tenant}' and cannot access the application '{appId}'({appName}) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.
Remediation	The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.