Nobody knows what the Nicolatians believed. It's one of the great mysteries of the Early Church. I'm intrigued that the two of you have each heard that their heresy involved organizational structure in some way, since that is none of the theories espoused by any of the early writers.
Irenaeus thought they were morally self-indulgent.
Victorinus said they ate the food of idols.
The Venerable Bede and Thomas Aquinas thought they were polygamists.
Can you tell me the source of your information that they had messed up church organizational structure in some way? I'm really curious as to how these ideas spread.