The connector on the uTrack back panel [USB B] for connect in interface mode to PC, MAC, or iPad
If you want to connect any HDD to the uTrack, you must use the [USB A] socket on the Frontplate of the uTrack24-.
Usually that cable are incluced to the USB 3.0 HDD’s. (USB micro B plug –> USB 3.0 A plug)

Hope that helps