citypass:

Buy a Dubrovnik City Card and visit the most popular attractions in Dubrovnik and its surroundings! This ticket gives you priority access to 12 top attractions in Dubrovnik, including the City Walls, Lovrijenac Fort, Rector’s Palace, and many more! Also, you will have an opportunity to enjoy free bus rides with the public transportation system.

https://wallsofdubrovnik.com/dubrovnik-card/

Dubrovnik’s Lovrijenac fortress welcomes visitors daily, not just from Croatia, from 8 am to 7 pm. You can visit it at any time of the year. You don’t have to pay any additional entry fee because the price is included with the City Walls entrance ticket. It’s very easy to get there from any part of Dubrovnik.