Mission Planner emulator: PreArm: check firmware or FRAME_CLASS

I have installed SITL from the simulation tab in Mission Planner 1.3.48, however I can’t move it from the disarmed state, due to this error message in preflight (and on the HUD).

As it’s my first time using this software, is there something I have missed in the setup or use?

Many thanks,

Found my own solution here: