<...>but after I pressed they essentially admitted that I won more than they bring in.
That's a scam, then. A proper casino should manage its bankroll in a decent way and never allow you to win something they can't pay out. If they do, by action or omission they are a scam. It's a pity that we can't do anything about them from here, as they are not known on the forum.
I don't think it's a scam if they have attempted to process some of the op's winning and maybe that's the only thing they can pay for now while they are still looking for more funds and settled them later on. The perfect term to call them rather, is unprofessional.
I agree it isn't a scam since the casino paid some of the money and I believe they promise to pay the rest when they have enough money. This case isn't new, as far as I remember there is also similar case where the complainant won a huge amount of money and the casino can't give him the winnings in one go. So the casino tried to pay him weekly until all his winnings is given.
It's not only about managing a bankroll but a proper/professional casino knows what are the things that is possible like what if some players win huge? They will think of ways on how to handle it, either by injecting more funds or by putting a bet limit on their games. Many casino have this function already. This casino here is not known in the forum before but now that this issue arise. Many are now aware of them.
I believe that casino doesn't think that someone will win a huge amount of money. I think they are relying that players will lose and they can accumulate huge amount from those losses and eventually their bankroll will have the ability to pay high rollers if incase they hit huge wins. but it looks like the huge wins comes early than the anticipated funds from player losses.
I can agree that there was a similar situation here, a gambling site which has thread on this forum.
I have read that they arranged a weekly or monthly payment to the user as they can't afford to pay it in one shot.
If the casino offered such payment arrangements, then, accept it. As long as they will pay you in the scheduled time rather than not receiving at all.
You can understand such situation will arise if the casino is not so big, and they can't pay up big winnings.
The casino should have put a bet limit if they can't accommodate such big winnings. I believe this will be their lesson on this situation.
The OP's casino I believe, doesn't have their own thread in the forum, so hard to reach out to them via this forum, better keep up with their site's support.