The 9 pin is early Can Am style trailer connector setup. Can Am did offer an adapter from round like you have to square like on the newer machines. Saying that, it should be doable, although you may need to ensure there is a good ground circuit on the trailer.
Years ago, by searching I believe here on Spyderlovers, others had posted the pin out for the round connector. Suggest spending time looking for it.
Attached is the pin function for the BRP module. The 4 Pin connector should be wired to pin A,B,H and J of the 9 pin connector. Does your trailer have a seperate turn signal light and brake lights? If so you need to go to a 5 or 6 pin connector on the trailer.
Please do not install that thing in your Spyder. There is a reason BRP quickly stopped using it. You did not tell us what year your Spyder is, but I assume it is a RT since it is in the RT forum. If your RT Spyder is a 2018 or 19. It will not fit anyway.
I do not know how good your wiring skills are. So this may not help. If your Spyder is a 2017 or older. That Y harness will plug into your main harness. So cut it off of the converter/isolator module. Then get something like this. https://www.amazon.ca/Reese-Towpower...%2C151&sr=8-12 This is just an example there are other brands. Just make sure you look for a powered one. Then wire the 2 together. This will give you a 4 wire plug that is power isolated.