After SSO has been enabled for the account, all users must log in with SSO going forward. This can be either from the SSO providers site, or by clicking "Log in with SSO" when logging in directly on the Periscope site. To directly access the login page, users must go through a link for their specific site. This should look similar to below:
Periscope supports just-in-time user provisioning. New users will be created in Periscope the first time they log in after being authenticated by the SSO provider.
Periscope does not currently support automatic user deprovisioning. To remove a user, they must be first removed from the SSO provider and then deleted from within Periscope.