We took the ferry from Playa Del Carmen to Cozumel, Crossed the street and walked to the right or South I believe for a few blocks then took a left . Sort of stumbled on to this place. The scooter was $25.00 USD for the day and a $60 cash deposit or give them a credit card # to hold instead. WE had not brought a CC so we used cash. They advised us it would be $5 USD to fill up the scooter with them or we can fill up at one of the gas stations. They provide you with a map. We waited 30 minutes just to get a scooter after paying and there at least 8 staff running around setting up bikes and customers.
When we returned it was different person working the counter. He said we owed him $10 for filling up the scooter and he didn't have any change to take it from our deposit. Luckily another group who had checked in with us advised yes your staff told us all $5. We just wanted to go but he made it so difficult and wanted us to go make him change because he had no money just our deposit. It just felt very shady. It was minimal annoyances but just wanting to pass along our lessons to others vacationing.
I however strongly suggest doing a scooter ride around the island we were able to go see many cool bars and beaches and be outside while doing it!