Generally, the best wiring method for CNC would be Bipolar Parallel. The motors draw 2.8A and have a best Voltage of 83 Volts.
For maximum power, you would need to have a power supply as close to that best Voltage as possible--And that would probably be 72V. If your board cannot handle that Voltage, then you should select a Power supply as close to it as the board will tolerate.
Make sure your printer port is operational--Print something. Make sure you are using a straight thru male/male serial dB25 cable.