Fortune Lounge has to pay, because the player met the terms and conditions that the casino set.
The casino was free to set any conditions it wanted to set. It set these, and the player met them.
If Fortune Lounge wants to change its bonus terms and conditions for future players, or eliminate bonuses altogether, Fortune Lounge is free to do this.
But if Fortune Lounge doesn’t pay this player, every reputable site will have to add Fortune Lounge to its blacklist, and that would truly be a shame. They would in fact be no better than Connecto and the other rogue casinos the poster listed above.
And FL had better pay this player quickly, or their reputation will be permanently harmed in any case.