Unable to Invite external users when configured to SAML SSO SCIM

Describe your question in as much detail as possible:
We are in Gold Plan trial version and we have just configured SAML SSO with SCIM provisioning. Is there a way we can invite external users who use a different domain such as gmail.com?
I create a GitLab account with my gmail and invited it from the Members page but I’m seeing the error below.
"garyl.paras: User is not linked to a SAML account and User email ‘garyl.paras@gmail.com’ does not match the allowed domain of ‘*******’

  • What version are you on (Hint: /help) ? and are you using self-managed or gitlab.com?
    We are using gitlab.com “GitLab Enterprise Edition 12.10.0-pre”