You currently add them manually to your Library. You’ll add them manually to a List.
And that’s okay.
You can enable/disable a lot of things with the Plex Sync settings. I’m not 100% sure as I’m not a Plex user myself but I’m pretty sure you can disable scrobbling and enable library sync only.
About Plex Pass:
Plex Pass is not required like it is for the Plex Webhook.
Just make sure you are using this: Plex Sync ✨
I know there’s some confusion about the different Plex Sync options.