Firstly, try the steps in this thread, make sure you’re putting in the same email that you used through Kickstarter:
If that doesn’t work check your Kickstarter account page and make sure the payment went through, and then also see if you have the confirmation and payment emails.
If you can’t access the download, and you definitely did pay for the game then you’ll need to contact radiant at contact@radiant-entertainment.com
Let me know what happens!