There seems to be some confusion on the official RB4 forums about the use of created characters. If what I am reading is to be believed, you can only use ONE created character and the rest of the band is automatically filled in with prefabs. There are reports that this is not just in quickplay but even in tour mode!
Apparently the problem on PS4 is that you can only have one player logged in to a PSN account and the rest have to play as "guest." That means only the player who's logged in has their score saved, etc. Someone reported that on Xbox One they are able to log everyone into the same Live account but they did not say whether each person could pick a created character.