OK, this is what I have about it.
Translation.
A - Mount with rivets on 3 supports that are mounted on the rear upperpanel.
B - Bolted (Bolt with locknut) on the rear sidepanels.
Attention this need to be watertight.
The rest of the text = about the sidespoilers.
You need to take the rearpanel with the Matra text of to mount this.
I did the same with my keefer spoiler.
Greetings Herman