Freefly RTK hardware doesn't have a radio to communicate between the pair of modules. It relies on the radio connection between the aircraft and the Ground station computer to transmit data from the rover (aircraft side module) to the ground station computer (base station module). You can use the Freefly solution for communication between the aircraft and the ground station computer (FRX Pro), but there are other options available from 3rd parties, such as the RFD900x.