You can adjust your bet to use less coins while spinning, but you must have enough coins for minimal bet to spin.
When you run out of coins you can purchase coins through a special offer or in the coins shop.
You can also collect free coins in the game. For more tips about that please see
https://helpitu.aquuuacasino.com/hc/en-us/articles/10111100450969-What-is-feed-feature-
https://helpitu.aquuuacasino.com/hc/en-us/articles/10108747843865-What-is-Daily-Bonus-
https://helpitu.aquuuacasino.com/hc/en-us/articles/10107503160601-What-is-Clam-Harvest-