HOTPROPS is a FPV racing simulator, where you can fly quadcopters and control them with your own RC transmitter. This is not a Plug&Play simulator - you have to setup some settings, before you can fly.
One of these settings is the transmitter setup. To fly the quadcopter with your own transmitter, you need an USB cable, dongle or audio cable. For more informations, please visit the manufacturer website of your transmitter.
You need some time, to setup your quadcopter to get real feeling of flying as you like.