This unit is designed to work with a ‘standard’ notebook power supply, which usually provides around 19 V/5 A. It will start to work from 5 V and its maximum allowable input voltage is 42 V. A decent, potent supply voltage/current is mandatory for the unit to operate at its maximum performance.
The board accepts a 2.1 mm barrel jack, as found on many standard power supply adapters. It supports any USB powered hard drive up to about 4 A. It should have no trouble powering your PiDrive.
Note: Neither the Raspberry Pi nor the hard disk nor the case are supplied.