When looking for answers pertaining to how to setup network connections or use Universal Control with your mixer, it's best to check out Section 3.1 (Page 12 for Ethernet and USB audio connections) and Section 11.1 of the Hardware Reference Manual on the downloads page linked. Permissions are discussed on Section 126.96.36.199 of the linked manual above.
Also, The Software Reference Manual has even more details about downloading Universal Control, what to expect when seeing a mixer connected, and even goes over other useful topics on connecting with Studio One 3 software and the like.
There is even some getting started StudioLive Series III Videos on our knowledge base.
You can always create a Support ticket with Your My PreSonus Account if you are still having issues. Make sure to Register your product and do any Firmware Updates before contacting support.