You just have to stick to legal, regulated online casino sites such as BetMGM, Caesars Palace Online Casino, FanDuel, Betway, bet365 and BetRivers. They offer great casino game ranges and they will pay out quickly and without any issues if you win.
If you're playing slots, approach the casino cashier and request cash from your casino credit account. Once your ID is verified you will receive your funds. Once approved your casino credit account is available 24/7.
One of the best slot apps that pay real money has to be the FanDuel Casino app, mainly due to the excellent selection of slot machines that they have available at the gaming site.