I’m on my cell so this might not be wel thought out. In any event the first thing that comes to mind is that that drive is really a gear box and that you are most likely using it in a reduction mode. If that is correct then you need to make 3.2 revolutions of the motor to get one rev off the gear box output shaft. That is 20,480 counts.
The trouble is this isn’t your counts per inch. To do that you would need to know what the lead of the lead screw is or the ratio to the rack. You don’t have the information needed for a complete answer.
I really don’t know. At this point we need more information to get anywhere.