The device is a whole new thing to Zack. He reaches out to poke at it, careful not to break it.

"You use this little box to travel?" Now he is confused. "Do I need money to get one?"

What neither of them know, is that the Nexus doesn't seem to want to let him leave. He'll be going back to an aeons-long abusive relationship with an evil hellgod brother, so something in the power here wants to cut Zack off, give him a chance. Still. They'll find out.