On page 4, there is an "IDE Power" connector. It looks a lot like a 4 pin CPU fan connector, but it (obviously) provides different voltages that are appropriate for 3.5" IDE drives (5V, 12V) and ...

The ribbon cable has a stripe, usually red, to tell you where Pin 1 is on its connectors. It’s finding Pin 1 on the device and on the motherboard that’s the real headache.