(Probably beginner) issue in intial setup

Need some help getting started. Followed the plugin setup guide as best as possible. Initially I followed this guide from you : https://pantheon.io/docs/wordpress-google-sso/ but some entries seem to be conflicting/incomplete (the SSO button does not appear with those instructions). Am a bit confused what needs to go where exactly since for exemple entity ID sometimes exampled as urn:wp-saml-auth and sometimes as the base URL of the site. I’m trying to attach it to G-Suite and since I probably have one or more params wrong, getting a “403. That’s an error. Error: app_not_configured_for_user” error. Do you have a full sample of a working functions.php with G-Suite ? Or do you provide private paid support ?

Kind regards,

Joris.