You mean Rollbit created an account for you? Or you already have one before receiving your first Bonus?
I’m sure Rollbit have a valid reason of restricting your account, are you able to contact the support and clarify this issue?

You’re one of the lucky gambler to received such bonuses, maybe there’s a terms for that and you just have to know it. Rollbit will surely communicate it with you as they have an active support.