SofoklisY,
There are plenty of other bit torrent applications that work fine with El Capitan while you're waiting for the specific BitTorrent application to be updated. You could use uTorrent, Transmission, Deluge, qBitTorrent, etc., etc., etc., etc.....
But for heavens sake, have a little patience. The developers are providing ALL these programs for FREE. You're not paying a penny. Neither is anyone else. And for some apps, they have to keep updating the application for every new version of Windows and Linux also, not just Mac.
Look: If you don't understand your current applications may not be compatible with a newer version of your OS, then you don't really have any business updating your OS. If you're too lazy to do your homework, don't update your OS. If you're not willing to use a different or new application to accomplish a task once you update, then you shouldn't update your OS.
So give it a rest, will you?