New PC no access to old pc cannot load libraries

My old Desk Top died (cannot access old one) and have purchased a new one with windows 11. Have tried to reestablish and or create new server but when I go to add libraries it keeps revolving back to download server.
Not too computer savvy so any assistance appreciated.

In order to complete the setup you need to open your Plex Media Server through its local IP.

If you’re on the same device… open http://127.0.0.1:32400/web in your browser. If you’re on a different machine inside your home network, use http://[PMS IP address]:32400/web instead. This will bring up a wizard/dialog where you can name your server and link it to your Plex account (as well as creating your first libraries).

Once you “claimed” your server (=linked it to your Plex account), you’ll also be able to access it from other Plex apps or via http://app.plex.tv/desktop.

https://support.plex.tv/articles/200288586-installation/