If you click the link in the e-mail they send you, it'll send you to the main Firefox page (not the "spreadfirefox.com" page) where you'll see a big green button for downloading. Unfortunately, the button downloads Firefox 2, not Firefox 3.
To get "Firefox Setup 3.0 RC 3.exe", you have to click the much less obvious "Firefox 3 Sneak Peek!" link.
What's the difference between "RC 3" and the version that's not "RC 3"? Does "RC 3" not count as part of the record? If it doesn't count, how would one find the version that actually counts?
-Bri