Trouble getting into "Preorder Bonus" page?

[Xemnito]

I Recently bought the game on steam, now I am trying to access the mods page which is locked. I followed the instructions, but the link "https://www.humblebundle.com/s?key=YOURCDKEY" does not work for me since I always receive a Error 404 when I try to go to the page. How do I fix this?

[EPR89]

Are you replacing the YOURCDKEY-part with your CD key?

Is it a 404 error or does it tell you that this is an unknown key?