Note that to use Luna Display in general, you must have a system with Windows 10 64-bit, Build 1809 or later, or macOS 10.11 El Capitan or later as your main PC. Again, this feature works whether the iPad is connected to a Mac or PC. Other additions with the Luna Display 5.1 update include support for Apple's Magic Keyboard and trackpad with a Luna Display-connected iPad. And if you're 'only' connecting a 4K screen, your refresh rate will be 60 Hz, whether the display is connected to a Windows or Apple system. If you're using a Mac with Big Sur or later, the refresh rate is increased to 45 Hz.

Any 5K screen connected to your Windows PC will be limited to a 30 Hz refresh rate, which is half the refreshes per second than what's typical (60 Hz).

If you plan to connect a 4K or 5K Mac, the machine has to be running at least macOS Big Sur.