On your first visit to Hydropolis during the story, you will need to find a way to meet with Leander and the queen. That will eventually lead to this sidequest, where you will have to deliver three packages for the equipment vendor. The first person can be found inside of the inn to the east of the vendor, while the second is found next to the item shop south of the vendor. The third package is to be delivered to someone in the southwest corner of the town, but you need to go through Nautes Harbor in order to get there. Once you’ve delivered all three packages, return to the vendor and you will finish the quest.