: I just found the URL, but part of it consists of my email address, so it
: would be different for you.

: I think they replied almost immediately to me.

Ah, you fill in the form with the URL .../download.php and it
immediately takes you to another form with the URL ../list.php
Since I didn't want to join a mailing list, I didn't fill that one
in, but it seems that that is the one that actually does the job
(I filled different information into the two forms to test this).
Then you get mailed a link to

http://www.washingtonwoodcraft.com/download.php?firstname=(1)&lastname=(2)?&email=(3)

where 1,2 and 3 are the things you filled in to the form at the .../list/php
URL. The software cannot possibly check the validity of (1) or (2), but may,
I suppose, check that you had previously filled in (3) and that it had not
got a bounce from that email address.... In a while, I'll try again using
that URL with information I haven't submitted through the form...

Andy