There are different requirements for different games but that doesn't really matter for this. In order for that extra $50 to be released to you, you are required to wager 10 times 250 (which is $2,500) in the casino.
For example if you deposit $200 you get a bonus fund of $50 for a total of $250. When you make a deposit you also get a small about of bonus funds that require a very large playthrough of 10 times the deposit plus the bonus. I have been accused of bonus abuse by ignition Casino.