[keycloak-user] Configure fine-grained authorization with SAML.

Hi, I'm working on Keycloak 3.2 to realize an authentication and authorization system for client applications that use SAML. I need to enable fine-grained authorization for a client application that uses SAML protocol, but I have find this feature only with OIDC. How can I configure and use fine-grained permissions also with SAML in Keycloak?? Thanks in advance.