1. Copy the compose.yaml from https://docs.linuxserver.io/images/docker-jellyfin/#user-group-identifiers and adjust, e.g.:

services:
  jellyfin:
    image: lscr.io/linuxserver/jellyfin:latest
    container_name: jellyfin
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Europe/Madrid
    volumes:
      - ./config:/config
      - ./media:/media
    ports:
      - 8096:8096
      - 8920:8920
      - 7359:7359/udp
    restart: unless-stopped

2. Run docker compose up -d

3. Navigate to http://<IP>:8096

4. Follow the wizard to create a user and libraries.

5. Profit

---

Steps for Plex:

1. Copy the compose.yaml from https://docs.linuxserver.io/images/docker-plex/?h=plex#umask-for-running-applications and adjust, e.g:

---
services:
  plex:
    image: lscr.io/linuxserver/plex:latest
    container_name: plex
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Etc/UTC
      - VERSION=docker
    volumes:
      - ./config:/config
      - ./media:/media
    ports:
      - 32400:32400
    restart: unless-stopped

2. Run docker compose up -d

3. Navigate to http://<IP>:32400

4. Create an account with Plex, give them your email and create a password with the specific requirements they impose. Agree with their use policy and confirm the pop-ups about ads and such.

5. You can now watch Plex media. Clicking your media will only have a link to https://www.plex.tv/media-server-downloads/

6. Look everywhere to figure out where to add your local media and give up.

7. Look in Google and no one has this issue.

8. Spend a few hours trying and give up.

BTW, the issue there that took me months to figure out is that while Plex documentation says that you only need to expose that port, it only works in network host mode, so unless you give it full control of your network it just refuses to work.