If you check your federation metadata file you can also use the uri in Custom to achieve the same effect.
F.e. : http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name for a name or http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress for email.
It depends a lot on the IdP which option you need to choose here. You could deduct it from the response. You might try Use Name ID to see if that works. But again this depends a lot on what is provided in the SAML response.
Can you pls add screenshot
First check Allow IDP Initiated authentication
Also add authentication classes in your configuration