Slide the four black Unistrut nuts into the 4 ends of your platform rack. Please note: the nuts should be placed in with the flat face down. Refer to the photo to see what should be seen.
Bring the rail behind the back of your platform and position it to be connected to the adapter brackets with another 4 channel nuts and M8 x 20mm screws. When you are satisfied with their positioning, tighten the screws in place the rest of the way. Please do not excessively tighten these, they should be able to be removed with a manual tool.