Not exactly. This is just a requesting frontend that can be accessed with either Plex/Jellyfin account or a custom one. Seer then has a contact with Radarr and Sonarr to automate their searches of media. Radarr and Sonarr is what is connected to a downloading client (either torrenting client, usenet or seedbox).

One can skip Seer and just use Radarr and Sonarr as is.