u/Classic-Warning5309

I have a 2010 Subaru Impreza and I’m trying to wire a subwoofer into it. The previous owner had it set up for it so I thought it would be pretty simple but I got a little bit confused when putting the RCA cables back to where they go, I found the green connector. that was unplugged and I didn’t know if it had anything to do with it. I’m just not sure if there’s an adapter I’m missing or something or if the RCA cables need to be connected to the stereo please help.