You can link both servers to the same account.
If you’ve set them up using different Plex accounts… sign into the one without the Plex Pass, go to Settings > [Server Name] > General and click on the sign out option at the center of that settings page. Switch users and go back to the same page to sign the server in with that account.
To be perfectly honest… I’m not sure I understand what you’re trying to achieve by keeping watched vs. unwatched (finished/unfinished) content on separate servers. If this is solely to deal with limited disk space on your main machine… why not just move the media to a secondary host and point the libraries of the primary server to this (e.g. by sharing the „archive drive“ of the second PC in your home network)?
I’ve tried sharing the main pc’s folder on the network but on the plex server I can’t find it to add.
It has nothing really to do with space. the one server currently contains everything thats finished (tv shows, etc) and any movies and such. The other server currently hosts currently airing tv shows.
I’d rather be able to put it on the one plex server shared but can’t figure out why I can’t see it when its already shared and then just remove the one server account.
Maybe let’s start with laying out your current setup…
You have two Windows PCs (PC1, PC2)
Both are hosting a Plex Media Server (PMS1, PMS2)
Each of those is linked to a different Plex account
One of those Plex accounts has a Plex Pass membership – for simplicity, let’s say PMS1 is the one linked with your Plex Pass account.
Drives on PC1 contain finished (watched?) media, drives on PC2 contain currently airing tv shows
You want to consolidate the two servers into one.
How did you share the drives of PC2 in your home network and how are you connecting them from PC1 (are you accessing the network path or did you map the drives with their own drive letter or mount them to a path)?