I am looking to create a game much like Highrise iOS, so in this game there are "Public Rooms" these rooms are premade and players can go in there and chat and play mini games. its basically a social interaction game. My question is i wanna have it so all rooms are enterable even if no one is there 24/7 so i think im looking to create a master server I wasnt sure if Low level API would do this or if i can just use UNET directly in engine to make a master server ?
You can build what you describe with either the LLAPI or the HLAPI. If this is urgent I'd suggest getting started with UNET tutorials so you can understand how it works.
If you have any familiarity with LLAPI, HLAPI and networking concepts then this should get you running pretty quickly: https://www.assetstore.unity3d.com/en/#!/content/71391 It's a free asset with fairly decent documentation and a demo that will help you work things out. With this you should be able to create a master server fairly easily. It works well with uNet, so once you're past creating a master server and registering your game servers to the master server, you can use uNet for all your other logic.
This thread is also kinda urgent. Please help. https://forum.unity3d.com/threads/create-gameplayer-after-gamescene-isloaded.457904/