If drives were not supplied, attach drives to side rails via slotted holes on the sides of the rails. The drives will then each have some adjustment front to back.
The mounting plate then slides on from the bottom front so the mounting holes line up. These four mounting holes are for attaching to the top deck of the autoloader. These mounting points have floating nuts so there is some adjustment at this point. Attach cables and power to the drives. Now would be the time to use the loader utilities from within the loader menus and calibrate the drive alignment. Swivel the entire drive cube if need be and tighten down the four large mounting screws. You may then make fine adjustments to the drives individually. Once alignment is finished place drive cover over assembly and secure bottom four screws to hold it on. (you may install the top four screws if you do not have a printer attachment.)
The back cover is now attached with the 10 screws provided.