We were just in Zadar last week, but with Royal. In our opinion it was too far to walk from where the ship docked. The day before the ship docked, we were able to book a shuttle through the Royal App for round trip transportation for $16pp. We chose our departure time for the shuttle from the ship, and then when we were ready to head back, there were plenty of shuttles waiting to pick us up and bring us back to the port.