Slot Rush is not an app worth using. You won't earn anything from it because it will not pay you, and you will just waste your time. Slot Rush is a mobile app that claims you can win massive payouts by playing.
That game is scamming you and never intends to pay. As you've discovered, NOBODY is paying you big money just to play games or watch videos. Feel free to play those games if you find them fun (some people do) but do not play them expecting to ever get paid.