You can read the Office of Inspector General's Full Report on the case here if you'd like.
Pretty awesome they figured out that there are certain times that a lotto ticket in that specific game has a +EV$ due to the roll down process of the payouts.
As someone who always laughs about the lottery being nothing more than a tax on the poor bc every ticket I had ever seen had a negative expectation, I think it's really cool a group of people found a way to turn a legit profit. Yes it took a specific set of circumstances due to a stupidly structured and flawed payout system that led to each ticket being worth a ~12-15% more than it cost, but more power to them for making a massive amount of $ off it.
Pretty interesting stuff in the pdf too about the logistics that go in to buying anywhere from 200,000 to even 700,000 lotto tickets for one drawing.