First, I'm not a Pyle tech. But back in the day I used to be an audio freak (1970's 4 channel all-the-way!)
* I tried to get the exact specs on your receiver but I suspect it's a non-amplified output. RCA jacks almost never have a high level output. (yes, the old 1940-60's used RCA jacks for speaker high level output. But you have a late model receiver.) Most likely you need a separate amp to power the sub woofer (unless it has it's own power amps.) You may still use another audio amplifier if you have a spare (mono or stereo won't mater as you only use one channel) but be aware that low frequency use way more power than normal frequencies (600 to 3KHz) The low end (50 to 300 Hz) will burn out any speaker and amp as the lower the frequency it's like hooking up a car battery directly to the speaker! If you have an old style vinyl record player that's playing a warped record. watch the speaker flap around to the wave of the record. Need to turn on the 50 Hz cancel out button to prevent speaker blowout!
* This link is still for a powered woofer. It looks like the same PD3000 receiver as yours though I can't be sure:
* This is an external "Powered" sub woofer (powered amp and additional cross over "filter" to extract just the lower frequencies. The following you tube link is a detailed example of how this type of system works: