Any chance you could share your embed code? I believe you should be able to subscribe regardless.
We are using Trusted Authentication. We were using restricted tickets and so the users were not able to see Subscribe icon. Then, we changed to unrestricted tickets and users started seeing Subscribe icon and create their own subscriptions. I wonder how implementing SAML affect the subscriptions - whether it is like restricted tickets or unrestricted tickets?
SAML being just another authentication strategy my gut feeling is that it would be like unrestricted tickets in Trusted Authentication strartegy.