Laurent Brugiere I think you can achieve your scenario with current predefined Privacy Policies if the user will have WP role: subscriber.

For the Space you choose: Public Privacy and for Course you choose: Private Policy. But if the Space is Public then anybody can join (so it is not your case I guess then). Custom Privacy policies dont exist yet. And you want Public Space with Admin approval/CRM automation to join in.

ps. if you your users will be admins that above scenario will not work since elevated acces gives some more power to the user.