Dubrovnik Airport: Take the Platanus/Croatia Airlines airport shuttle, not a pre-booked private transfer: it meets flight patterns, runs via the Old Town/cable-car stop (Petra Krešimira IV) and continues to Gruž bus station. Allow roughly 35–45 minutes to Pile/Old Town area and about €10–12 one way. Buy at the airport, online, or at Gruž; departure timing is flight-led, so check it on the day. A taxi/Bolt makes sense only for several people or a late arrival.
Dubrovnik Main Bus Station (Gruž/Kantafig): For the Old Town, use Libertas 1, 1A or 1B from the main road outside the station to Pile; allow 15–25 minutes depending on traffic. Buy a kiosk ticket rather than paying onboard: the evidence lists a roughly €5.31 24-hour pass, while onboard tickets cost more and cover one ride. There is no rail station in Dubrovnik; intercity coaches are the practical overland arrival.