It seems you want to turn off Automatic User Provision that will auto create user if user not exist.
This feature can be disabled in SP Connector Internal Setting.

Usually user will be redirect to your external IdP(Azure, Okta, etc) for authentication.
After authentication, user will be redirect back to OutSystems.
At this point, if user not exist and Automatic User Provision is disabled
User_Check action will return invalid and error message will be displayed. 

Regards
Wei

Hi @Masahiro Harahata 

Turning it off changes the authentication model significantly:

• New Users will be blocked
• SAML Attribute Updates won’t propagate
• There would be risk of Identity mismatch
• Increased Administrative Overhead