Select and hold the green Spin button in the bottom right corner for about 4-5 seconds to toggle auto-spin.
Your game will spin independently until you tap the button again, change your bet, or leave the game. If you encounter a bonus game which requires your participation (eg. selecting one of three mystery bonuses), the game will wait for this action before continuing to spin.
You can tap the reels to speed up your spins or skip animations during auto play.