It should be written on their terms, because if not, then that casino is a scam. Though this kind of casino is really unfair for the new, for sure it is newbie friendly because you are forced to play your deposit until you meet their requirements. For those who are heavy gamblers, this is fine because they can easily achieve those, but for those of us who are not as heavy gamblers, it is a disadvantage.
I think if a casino is operating legally and has some kind of license, the terms of such a casino would surely spell out information about mandatory wagering requirements. The problem is that most casinos prefer not to advertise that, and it may be very difficult for a beginner to find this information, especially if the Terms of Service are written in small print.
It would be great if many casinos notified users of the need to make mandatory wagering before a user makes a deposit.