You just need to progress in the main quest, aka the quest line with Foxot's father in Piratetown
23 days ago (+1)
Check your quest journal, and see how far you're into the "Piratetown" quest. You need to talk to Xero in front of Vulfox' mansion, then talk to the lighthouse keeper, then jump into the water in the middle of the town, and swim all the way left to enter the mansion. The Quest Guild Recommendation is a reward for completing that quest. Once you've got it, enter the building right to the quest board
23 days ago (+1)
There's a little warning on the game's front page about that. Spedumon, the developer, uses RPGMaker for this game, and the program doesn't like older save files in newer versions with scripts that can't be triggered anymore cuz you moved past a certain point in the game. Try to re-download the game, and use the prepackaged save files that come with version 0.19. Save file 02 puts you in the pirate ship just before you're about to enter Piratetown for the first time. The characters are all decently leveled, everything that can be done on the previous islands has been done, all scenes unlocked and items collected up to this point, so you won't be missing out on anything. Just make sure to spend all your free stat points, and change the equipment to fit your playstyle. Yes, the bunny is now simply called "Adventurer", but you can return to the ID machine in the Gloomy Forest, to change your name.