Platanus does not sell tickets on the bus (its FAQ is explicit). Older guides still say 'pay the driver €8' — both the €8 price and the cash-on-board habit are out of date. Show up with only a QR code bought online, or line up at the arrivals desk first.
The Old Town stop is Ploče Gate on the east side; the cruise-side western entrance, Pile, is not served. Taxis and Bolts also drop at whichever gate is nearer your address — everything inside the walls is stairs and stone, with luggage carts banned. Hotels with walls-adjacent addresses can mean a 5–10 minute carry.
Dubrovnik Airport's own site says the drive averages 30–35 minutes but to plan up to an hour in the summer months — July–August traffic on the coastal D8 plus cruise-ship days can make 20 km take 90 minutes. A ferry or organized transfer booked tight to your landing time will not wait.
The airport lists lines 11, 27 and 38 as public transport, and they really exist — but they follow school-and-shift timetables; current schedules do not show all three running every day (lines 11 and 27 have no Sunday/holiday service, 38 is limited), and reaching the walls often means a change in town. Missing one can cost an hour of waiting with suitcases on a roadside stop.