arielzusya
The only things that dictate this are the main Enable Knowledge Base setting, the Require Client Login setting, you need to have at least one Public FAQ Category, and you need to have at least one Public FAQ within that Public FAQ Category. Since you said you enabled the main setting, you enabled the Require Client Login setting, the User is Logged In, and you have a Public FAQ Category it sounds like one of handful of things. Either you don’t have a Public FAQ within your Public FAQ Category -or- maybe the code has been messed with and not working properly -or- something is borked like db records or code. I would first double check all of the setting/configuration options before looking into the database side and code side of things.
Cheers.