Cash Slots is not giving away real prizes, so you won't get paid even if you meet the conditions. It's important to mention the developer's goal is to hook the player on the game for as long as possible. The reason is that the more advertisement they watch, the more revenue the app generates.
All in all, there are free slots that pay real money, but you will have to be playing at real money online casinos as opposed to social casinos on slot apps, or playing titles in demo mode.