I used CLI for setup, the GUI is just for ease of file management and checking libraries. I recommend hotio for super easy images to just fire and forget. Links I hope will help you: hotio.dev/containers/jellyfin/wiki.servarr.com
Step 1. Get docker up and running (Portainer helps with other containers) Step 2. Use prowlarr to set up all the search engines you’ll use on other *arr apps Step 3. Set up your libraries with Jellyfin