OVK Hydraulic Fridge Slide

I recently bought this off marketplace and after spending a few hours trying to get this to fit, I decided I’m just going to get something smaller. I have this mounted on a deck box so the issue I’m running into is getting the back seat to prop back up and catch. So currently the 60 portion of the seat is down. I know the person I bought it from was able to make it fit so I really am not sure why it won’t for me but I think if it’s mounted on the floor it’ll have a better chance at fitting.