After I completed the quest "Coming to terms", I was able to ask Luca to work on my ship. However, it is possible for me to repeat asking him to join even he is already working on the ship.
Besides, there was a woman called Kalei, who asked me came closer to talk when I left the company building. After i clicking on her, she just said" Be seeing you" then walked away. I am wondering it is a bug or not.