This mount is designed to be both the inner Y rail corner support and the Y motor mount. it bolts onto the inside of the two rear 20mm extrusions and the Y rail extrusion. The motor mounting screw locations are designed to be recessed. M3 screws with 8mm washers for the motor mount, M5 screws with 9mm washers for mounting to the frame
EDIT: the mounting holes for the NEMA 17 motor were too close to the back frame. moved them, works fine now.
Should print fine without support and bolt right into place