If you were to ride a bike down to the beach where would you put it? And would you be fined for not having some kind of like, sticker?

Just go to the beach people in Little Compton don't steal don't worry about your bike just enjoy South Shore

Keep it with you. No sticker required & you wouldn't have to pay to use the beach.

Bring a lock with you some areas have bike racks or chain it to something sturdy , when in doubt ask an officer or worker