In the airframe screen, under the Rover configurations, select the Generic Ground Vehicle airframe preset. The QGroundControl user guide provides more information on how you can select this airframe.
As of 1/22/21, PX4 and QGroundControl now have an option for the NXP Cup Rover when setting up the "Airframe". Instead of Generic Ground Vehicle as pictured below, use the drop-down menu and select the NXP Cup Rover airframe.
