I didn't follow any single guide, but the following got me through my installation:

• Install Plex Media Server using DEB or RPM repository

• Plex file naming conventions

I used Dockstarter, since I am relatively unfamiliar with Docker. If you haven't heard of it, it is essentially a GUI script that helps you with directories, ownership, and settings involved with a large selection of Docker containers. It tends to focus on the linuxserver io releases.

• I like qBittorrent, and this particular image worked best with my VPN (AirVPN): Dockstarter: qBittorrentVPN. The linked support forum was helpful figuring out a couple of OpenVPN specific issues I had.

• Dockstarter: Prowlarr

• Dockstarter: Sonarr

• Dockstarter: Radarr

The Trash Guides are useful for setting up the directory trees.

• https://trash-guides.info/Prowlarr/

• https://trash-guides.info/Sonarr/

• https://trash-guides.info/Radarr/

There's also a list of suggested Plex server settings on that site.