For a private portal you need an access (Login). Without this Login you don't see any elements of the portal.
In a public portal every user can see menus, content and other functionalities, which are activated for guests. But you still have a login area, where users can log in - as far as they have login data - to see advanced content or to get access for administrative features.
You can change the settings in the Portal Manager. Go to
Tools & Administration > Portal Settings > Login & Password > Section Portal Access.
Don't forget to save.