SSO auto create users —> CB users table

Similar questions have been asked before, but not this situation specifically. At the insistence of a client I am using the SAML2 SSO plugin from miniorange.com to utilize the client's ADFS IdP. It is working and Joomla is automatically creating users, but of course, they are not in CB. Is there a way to redirect auto-create to the CB API, or a trigger to run the sync users routine on creation of a new user? What's the best approach to take?

Your plugin would need to use CB API to create users. That's the only way for it to properly handle integration with CB. Running Tools > User Synchronization is not a means of doing this as it bypasses all checks and is just there to migrate an existing Joomla install. See the below tutorial on how to register a user using CB API.

www.joomlapolis.com/documentation/279-community-builder/tutorials/18362-registering-a-user-through-cb-api