Also check out Ombi once you have the arrs set up. It's a combined UI for your users (or just yourself) to request a movie or show and then you just wait a bit and it shows up in Plex/Jelly.
Maybe it's just me, but ombi was no end of issues for me (and resource hungry). I switched to Overseerr a while back and haven't looked back. Would highly recommend giving it a try.
I found it to be a very polished experience and has been set and forget.
It's funny, I've heard of radarr and sonarr, but I never looked into them because I was learning other stuff.