You will get different answers depending who answers. The motor currents are dynamic and constantly changing. If all your motors are ON then the sum of the average motor currents is what is drawn from the power supply.
The motor currents are different for different connections like SERIES, BIPOLAR, UNIPOLAR. The bipolar connection uses the most current, 2.8A in your case.
You could start with the sum of the average motor currents and then take 75% of that as your power supply current. It is unlikely that all motors are on full bore at the same time for an extended period of time.