I am not a linux user and I know little about how to set up a seedbox, but there is a very simple way to get it set and ready(using the commands below):
the error code came to you is about creating a .torrent file, it seem some is wrong with it. If you are not good at using linux, just re-install the rtorrent and rutorrent. I've done it twice, and problem solved both times.
wget --no-check-certificate -O autodl-setup http://sourceforge.net/projects/autodl-irssi/files/autodl-setup/download
sudo sh autodl-setup