The Pioneer receiver has a sub out that would connect with a single RCA cable to the LFE input on the sub.
The receiver has a speaker set up menu. If it says none then it won't send anything to the sub. There is also a subwoofer level control in the menu. The default for that would not be all the way down but check it. Set the front speakers to small if you want the sub to work more. When you set the fronts to large the sub becomes a low frequency effects speaker and doesn't play as much since a lot of bass will go to the front left right speakers.
To check if the sub itself works you can connect your phone to it. Be careful with the volume on the phone. Don't want to break what ain't broke.
Check the level on the subwoofer too.
Polk...