Jellyseer is a Jellyfin/Emby-compatible fork of OverseerrOverseerr, a request management and media discovery tool built to work with a existing Plex ecosystem.
Once you've enabled it in your account, launch the app via your dashboard. You'll need to perform the initial setup, either by signing in with your Plex account, or your Seedplicity JellyFin/Emby account (use jellyfin:8096 or emby:8096 as your hostname) and connecting to your apps of choice (see Interconnecting-Apps)
Relevant details copied below:
jellyfin8096emby8096plex32400radarr7878(get api key from UI at Settings -> General)sonarr8989(get api key from UI at Settings -> General)