If you're looking for this, what you want is at https://github.com/fedarovich/qbittorrent-cli
You can then add torrents by magnet link or torrent file through cmd.
example:
qbt torrent add url %1 -c Movies --url http://192.168.2.13:2222 in a .bat file where the argument would be the magnetlink, for downloading in the category Movies. The ip and port (192.168.2.13:2222) is my example, yours may differ.
Associate this bat file with magnet:// links in your browser, and you can download those on your remote server by just clicking those links.
With a little bit of extra work you can also download torrent files this way.
For a slightly more complex example where you can choose category:
@echo off
echo Downloading magnet link
echo ------------------------
echo 1. MOVIES
echo 2. SERIES
echo 3. GAMES
echo 4. APPS
echo 5. TUTORIALS
echo ------------------------
choice /C 12345 /N /M "Choose category: "
if ERRORLEVEL 1 SET category=Movies
if ERRORLEVEL 2 SET category=Series
if ERRORLEVEL 3 SET category=Games
if ERRORLEVEL 4 SET category=Apps
if ERRORLEVEL 5 SET category=Tutorials
start /B /I /MIN "" qbt torrent add url %1 -c %category% --url http://192.168.2.13:2222
exit /B 0