Content rating restrictions are part of of the parental control settings that let you control what folders, playlists and files are delivered to your devices and users based on content ratings so that your children do not watch or listen to content that is not suitable for them. Mezzmo Windows has extensive parental control features for setting up content rating restrictions. See Using parental control settings.
If you have set up content rating restrictions for your Mezzmo server, then you can bypass them in Mezzmo Android using a PIN code.