Royal Pass is a seasonal offer that can be purchased once a month. If a decision to purchase the Royal Pass is made, it will grant access to a Royal set of rewards in the Blast Royal event. Rewards from Free and Royal sets can be only claimed manually. 

Upon purchasing the Royal Pass, you will also notice that the life cap has increased from 5 to 8 for the duration of the Blast Royal event. 

You can access the Blast Royal event and rewards menu by tapping the chest in the upper right corner of the game screen.