Plex DVR for premium channels?

I'm confused whether the Plex DVR can record only free over-the-air channels, or any channel coming through my cable box. I have a cable subscription, so I'd be getting the HDHomeRun Prime box. Can Plex DVR record any show I get through that box? Or only free shows via the digital antenna? Do I even need the digital antenna if I'm not utilizing the free shows?

Thanks!