Ok. I’m going to assume you have zero networking experience, and have one computer (a desktop/laptop). I’m also going to assume you are using some flavor of screen mirroring tech (eg a Chromecast) to wirelessly connect the
Per your post the goal is to A) download items, B) store the items on local disk, C) display the items on your TV via some kind of wireless.
I’m further going to assume we are strictly working with torrents.
You will want to download two applications, 1) a torrent client (I’m not going to recommend one because Im not up to date on the differences), and VLC. You will also need whatever application your VPN requires but I think you have that configured.
When downloading via a torrent you first turn on the VPN prior to downloading/seeding/etc. Once the torrent is finished, you can send you content to your TV via VLC (there is an option to use the TV as a renderer target).
Some gotchas. Unless you configure your VPN to allow local traffic, all traffic goes via the VPN. This means that your computer is completely isolated from the rest of your Network (it’s visible, but can not interact with any of it). If you want, I can go into the hows/why’s of what’s going on. For the Pi. Use it to learn and play with Linux for the time being - focus on getting comfortable with the shell and do not attempt to run a reverse proxy/web server unless you understand what’s going on (this is to keep you safe).