It is possible to SSO into WordPress from ADFS using our SAML SP plugin. You can test the SSO connection using our free version of the plugin: https://wordpress.org/plugins/miniorange-saml-20-single-sign-on/ For authenticating users with ADFS, your site should run on https. The connection will be direct no third party service is involved i.e. traffic will remaining between your WordPress site and ADFS.