Hey, I've used your site many times since I've had my server (every re-roll I come back for reference). It's really a wonderfully comprehensive guide.
I see a lot of people wondering about the "auth" file. its location seems to have changed since the original writing. the new location is
"var/lib/deluge/.config/deluge/auth" and it should really read "deluge:deluge:10" since deluge seems to get confused without a user level set.
the reason is that deluge now creates a folder in the users home directory called "~/.config/deluge/" so that each user can have different configurations. since we set the deluge user's home directory as "/var/lib/deluge" the path gets a bit convoluted.