All the downloaders that I find only downloads to the server and I only want a UI without ads to make easies to use yt-dlp without the terminal.
Metube can do that, but that’s also not what OP asked for since he does NOT want to store the files on the server.
This MeTube in a local docker container seems to do what OP wants:
https://github.com/alexta69/metube
tag /u/kutu-dev
I have MeTube running, it does not what OP wants (unless he reconsidered) because it downloads the files to server storage.
But you can just start the container on his PC, then the Server is his PC?