It seems it is run out already, I just created an account but I get no free bet. I'm not really sure if there is something need to be done to get it but there is no explanation to get the free bet so I think it should be added automatically when a user create an account. So I guess there were more than 333 registered users already who received the free bets.
The 4D lottery reminds me a lotto game which is so popular in my country, the difference is that there is no option to bet on 2D or 3D digit numbers in this site. I believe it is so hard to win 4D lottery game, but the main important thing is that I do not find anything related to the provably fairness to draw the numbers.