You need to enter your serial number - there should be a register button next to the plugin in Help>ABout installed plugins, the serial number is on the Available serial numbers page of your account. Once you've entered it an clicked Accept, restart DAZ Studio. The content database is what you see when you view as categories - it has nothing to do with content directories, which are managed via Edit>Preferences>Directories (remember to check all three lists, by clicking the button at the top of the dialogue).