If
THIS is your motherboard, then the ports numbered as 17 in the picture below are your USB 2.0 ports.
You can plug the D5 Next's USB connectors into any of the four rows of the two USB 2.0 ports.
It doesn't matter if it has 4 or 5 pins, the 5th pin on the one row is for cable shielding, which is not used in this case.
If you like, you can connect both pumps to one of the ports, leaving the second free.
Polarity is important... the black wiring on the D5 pump's connector should go to the end with the missing pin on the 4-pin row of the motherboard's socket.
usb_ports.jpg