a-train VS autoscan

A-Train, Autoscan's Google Drive integration, only supports Shared Drives and requires Service Account authentication.

Use Cloudbox/autoscan instead. Plex Autoscan is not maintained anymore, you can see the repository is archived.

If you use *arr to manage your downloads try setting up the "Connect" section of it with Plex and only scanning when you import/add new media to save on the periodic scans for no reason, or perhaps check out https://github.com/cloudbox/autoscan as I've heard good things about this as well.

You should now use this instead: https://github.com/Cloudbox/autoscan

This tool is designed to let sonarr/radarr directly communicate with tdarr, much like autoscan is able to communicate between sonarr/radarr and plex/emby/jellyfin.

The solution to have plex refresh the metadata after a bazarr subtitle add is to use autoscan. NOT plex_autoscan, but autoscan. This is the newer version. You also need autoscan-adapter, the critical piece of the puzzle. Autoscan by itself lets bazarr/sonarr/etc notify plex to update libraries. The autoscan-adapter helps autoscan be able to actually refresh plex metadata so the new subtitles from bazarr can be found. This is all actually very easy to implement using docker-compose. Refer to the docker-compose setup in the autoscan-adapter github.

I recommand using Autoscan. If you're using the *arr stack to download your medias, it can then automatically trigger a scan. The *arr stack can do this without autoscan for jellyfin, but the advantage of autoscan is that you can plug it to any of your other means of downloading medias by just calling its webhook