Honestly hadn't noticed the name of the band, so I was confused as well. Probably would've been more clear if question was worded 3rd Green Hat band member or something like that. I literally thought OP was searching for a green hat👒 which caused my head to do a wth tilt...
(also he/she clicked "it" not "him," effectively objectifying the poor leprechaun)
When you clicked on the 3rd band member, did he go up by the others? He's supposed to & then you talk to the band before the door opens to the luggage room.
If nothing happened after you clicked him, verify the other 2 are I we by the luggage already. If they are, I suggest clearing the game cache / cookies & refreshing the game. If still no joy after clicking all 3 band members, you'll need to contact SUPPORT via the button under the game settings wheel (upper corner of the game window.)