Advice needed on how to connect the output of the pixhawk with a command on a joystick

Dear reader,

For a project I am trying to control a brushless DC motor. In order to do this I need a pixhawk to send an adjustable PWM signal towards an Arduino. The joystick that is bought is of model type: Futaba TS14SG.

There is documentation online about tuning the controller, but it is unclear for me (probably I dont understand) how this relates to choosing an output pin and how to set the PWM for each joystick button.

Any information or advice is welcome!

With kind regards,