Hi @joe.abraham,
Thanks for the update.
Unfortunately, as you have discovered, the Pre-User Registration action only works for database and passwordless connection users. It will not work with enterprise connections.
And when using an Enterprise connection, there is no option to disable sign-ups. This is because the sign-up happens at the IdP and not at Auth0.
Is your current application allowing multiple types of connections to authenticate? Like email + password, and enterprise connections?
Thanks,
Rueben