I'm having the same problem on my Phantom 4 Pro with a USB cable on my Android Nexus 5 phone. I have made sure no apps are running, power up the controller, then the aircraft and then open the app. It gives me the option choose DJI GO or DroneDeploy. I choose DroneDeploy, select a flightplan and get nothing but crickets and " 'connect a drone to fly'.
My Nvidia Shield will arrive this week and I'll see if I get a different result.
p.s. sorry for the threadjack, but it seems like a potentially related issue since we're both getting the same error message.