Connecting to Rumba Board


I’m trying to connect the Discov3ry to my Rumba Board for my modified Rigidbot printer. Wiring seems straight forward, the Rumba Board is labeled with A1, B1, A2, B2 so just followed instructions in the Discov3ry card. I can’t figure out the steps to set the extruder at in the Marlin software (#define Default_axis_steps_per_unit). I got some buzzing sound at 10,000 one time and then it stopped. I tried increments between 1000 and 15000. I plugged in a linear actuator I have and its not the stepper motor because that worked fine. ???
Any guidance would be appreciated.