Overview

Looking from top down:

1. Prowlarr:
   Is basically the indexer which is crawling in the internet and searching for the requested torrent files. It's the management of both Torrent Trackers and Usenet Indexers
2. Radarr:
   Is a movie collection manager for Usenet and BitTorrent users. It can monitor multiple RSS feeds for new movies and will interface with clients and indexers to grab, sort, and rename them.
   Short: it gets the metadata for the Movies
3. Sonarr:
   Is a PVR for Usenet and BitTorrent users. It can monitor multiple RSS feeds for new episodes of your favorite shows and will grab, sort and rename them.
   Short: it gets the metadata for the Servies / Shows
   
4. qBittorrent:
   Is the application which is downloading the torrent. It's good if you use a VPN or proxy socks to not expose your public IP address.
5. Filesystem:
   Enough space to download movies and series. It's recommended to use the provided folder structure.
6. Jellyfin:
   A server media player which shows the downloaded movies in a nice view.
   
7. Jellyseer:
   application for managing requests for your media library. It is a fork of Overseerr that has been specifically built to support Jellyfin. Short: it allows you to request new movies to get downloaded. Works together with jellyfin.

How it will work at the end:
You can search any movie / series on jellyseer. Then you click Request and it will download you the file and jellyfin automatically shows it in your library where you can watch it.
In the background happens following: Prowlarr is providing the torrent for the file while qBittorrent is downloading them, sonarr/radarr are adding the metadata to it (movie name, release year which is getting the info from IMDB).
Jellyfin then will add the movie to the library.