I'm sure the hotel is willing to charge an exorbitant amount to arrange a car, but excluding that you have four options: taxi, rental car, shared shuttle van, or bus + taxi. I was there with a fellow FTer recently and we did the bus + taxi as you can take a bus from CUN to downtown PDC. The cab is about a 300 peso, or $15 ride from there. Bus is like $10. A taxi from the hotel back to CUN was 1200 or 1500 pesos, I don't remember. Unfortunately there is no Uber in PDC, so you're subject to the taxi mafia fares. You can look up the prices for shuttle van transfers, USA Transfers and Canada Transfers are both generally well regarded.