I'm not familiar with that controller, but looking at a manual online, it looks like it has a switch on the back to change between different pairing modes. Make sure it's set to either bluetooth or dongle mode if you're connecting it to a PC. It says it should show up in the Windows bluetooth pairing settings as "Xbox Wireless Controller". So make sure it's paired to the PC like that. If it's still not showing up, then sorry, I don't know why it wouldn't work in-game. Unity may just not be recognizing it for some reason. You could try a different controller, or play with keyboard controls instead.