Plex on Umbrel home - New setup

Hi all

Please could I ask for some assistance. I have been using Plex media server for years now, just running a server on my home windows machine, and then connecting to it from my media devices on my two TVs in the house.

I now have an Umbrel Home. All I want to do is be able to add my media library to my Plex running on my Umbrel Home server. But I am at a total loss. I cannot figure it out.

I created a new Plex account. I don’t even mind downloading all my movies again. I installed Transmission on my Umbrel. How on earth do I connect a media library that is on my Umbrel, to the Plex running on my Umbrel. I feel like a total idiot and that this should not be this complex but I truly cannot figure it out.

Any help appreciated. Thanks!