You’re just a step away from getting your own ship and leaving this island. To start off, head to the dock in Sami and talk to the shipbuilder.
Next, travel to the Pronnoi Peninsula. If you have synchronized with the Star Observatory there, then you should be able to fast-travel to the nearby vicinity. Once there, you need to deploy Ikaros to scout the area. After finding the Cyclops and tagging his men, approach the abandoned town.
However, you won’t be able to whittle down his men since as soon as you set foot in the immediate vicinity a cutscene will play and you’ll have to fight the Cyclops and all his men at the same time. Be careful of his archer as well since he can unleash annoying poison arrows. If possible, prioritize this guy who will be actively running away from you and reposition to get a clean shot.
Avoid getting surrounded by running around and funneling the enemies through the narrow paths and ledges. The enemies aren’t as agile as your character so you can use that to your advantage. Jump across ledges, climb to higher areas then attack enemies as they use the ladder.
Keep doing this and using your own arrows to damage them as they attempt to approach you. After dealing with the softer henchmen, you can focus on the Cyclops. Take him out to complete the task.
Return to the prisoner and free him. Follow the prisoner and escort him to safety. Once you reach the outskirts of town, a cutscene will take place. You’ll meet Barnabas, the captain of the Adrestia. He’ll travel back to Sami where the ship is docked.
At this point, you just need to talk to him in Sami’s harbor to hop aboard and take control of the ship. At this point, I’ll recommend wrapping things up in the island like pending sidequests. When you’re ready to leave, talk to Barnabas to complete the quest and officially start your real journey.