In the versions greater than 10.2.x, (or the 'new' Lite version), in the settings "FEATURES", click on "[Adult] Enabled?, which will allow the password entry to be enabled, and will then show the adult channels, which will require the password to be entered to open a channel.
It isn't very secure, as there is no check against allowing the password to be changed.
Sometimes, if you don't have a valid login to the server, the add-on could load up the unprotected adult channels from the server (these are just copied links, not specifically created for the server, and don't require server validation). If you don't have a password set in the older version of ISP, you will be able to view the adults without entering the password.