The list you are referring to is a list of subscribed people who sign up for these sorts of promotional material which comes from a third party subscriber company.
They may not have heard of that casino. But Yaniv said they were people that signed up to receive offers like this from a 3rd party. There’s a million places I see all the time that when I join it asks me if I’d like to receive special offers from their partners, etc, also. In which case, if this was one of those offers they wouldn’t have necessarily heard of the casino specifically.
I hope that made sense.