How to conditionally show content if user is logged in

You can check the logged user session in this case.
When your users log in, a session is being created. Its name is security provider step name + Id. If your security provider step (in server action) is called "userSecurity" the session will be called:

userSecurityId

In order to check this, in app connect structure add session manager, and add this session there.
Then use the dynamic attributes - show - and select the session as a condition.