Water Pump Controller

Hi Guys,
Currently, i’m building a Heavylift Hexacopter for crop sprayer.
i have a problem settings up the Water Pump Controller.
i try to follow the documentation on the ardupilot.org, but it is still not working.

i’m using water pump controller from foxtech : https://www.foxtechfpv.com/water-pump-controller.html

is there any proper documentation for this controller and how to integrate it with arducopter ?

Thank you.