How to enable automation hub for everybody in the company?

We want to enable everybody in the company to be able to submit automation Ideas under their respective functions. We have enabled SSO, but when a user logs into automation hub, they get “no access” message. Apart from adding each and every user in the company into automation hub and assigning them a role, is there a way to assign a default role of “Standard User” to everybody that is an SSO authenticated user ?