Instead of manually registering a SAML 2.0 client, you can import it via a standard SAML Entity Descriptor XML file. There is an Import option on the Add Client page.

Click the Select File button and load your entity descriptor file. You should review all the information there to make sure everything is set up correctly.

Some SAML client adapters like mod-auth-mellon need the XML Entity Descriptor for the IDP. You can obtain this by going to this public URL: root/auth/realms/{realm}/protocol/saml/descriptor