I've been trying for a few days to get end-to-end AD authenticated access established for the Azure Synapse Serverless SQL Pool with some progress but no end-to-end workable solution until today.
I tried creating a SQL Server login for an AD security group using its domain, e.g.
CREATE LOGIN [UG-DataAccess-Confidential-RO@domain.com] FROM EXTERNAL PROVIDER;
and received the error
Principal 'UG-DataAccess-Confidential-RO@domain.com' could not be found or this principal type is not supported.