Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

Exactly the title. I'm researching having a jellyfin server and downloading media seems like it would be tedious (the way I've done it once or twice previously). I could use some clarity on what Sonarr is, what it looks like (like is there a GUI?? I'm too stupid to run something off of a terminal), and how it works. I'm familiar with torrenting but not with usenet, and I use the megathread from this community. Can someone explain Sonarr/Radarr to me in a way that would be understandable to someone at my level of understanding?