They actually bought a copy of the source:
I'm confused about what it is that site is gambling. What are the "coins"?
I made a steam account and deposited $5 worth of BTC into it. How do I get 'coins' to play with?
quoted from https://www.csgocrash.com/faq
A coin is a one thousandth of a dollar ($0.001). Coins are backed by Steam skins. You are able to deposit and withdraw coins at any time by going to your account page.
To deposit, head over to your Account page. Make sure your trade link is properly set. Once you’ve done that, go to the Deposit page, select up to 10 items and then hit Deposit button.
Keep in mind that some low-value or low-popularity items are not depositable.
Make sure the security codes on both the trade offer and the site are the same
So im guessing your steam