Due to an unfortunate oversight, you may have an M3 x 20mm bolt instead of an M4 x 20mm bolt and the 3D printed KIS3R33S bracket will have a 3mm hole instead of a 4mm hole. If this is the case see the next step.

Take the KIS3R33S bracket and use it to mount the USB adapter to the side of the PSU with an M4 x 20mm bolt.

Connect the wires to the +/- terminals as shown. Red to positive and black to negative.