Unlike the Galil series of cards, the Acroloop cards had to be ordered as either servo or stepper.
If you have the servo card then there are rafts of servos that use ±10v analogue, which is what the ACR uses, on your attached docs. the pin 1 is the analogue ± and pin 20 is the complementary common and so on for pin 2 and 21 etc.
The encoder input uses differential or single ended and with the internal pull up resistors can be used on 24v type also.
I have used the ACR8000/2000 extensively, with the Acroloop DOS software, AcroCut, Acromill etc.