Issue:AADSTS90072: User account ‘XXXXX’ from identity provider ‘XXXXX’ does not exist in tenant ‘XXXXXX’ and cannot access the application ‘XXXXX'(Azure DevOps) 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
Solution: User account should be added to Azure Active Directory to get access to Azure DevOps. Incase you are not able to add the user to Azure AD contact the Active Directory Administrator to get them added. Otherwise you can add users as external guest users but not sure whether it’s possible.