I believe I've got the "typical" usage straight now...
create single "user name" for an expected individual user (makes sense in retrospect).
Link each unique device (default is device hostname, but can change) to that single "user name".
So, for example:
single user name = "FU.BAR"
linked device = "my PC 1"
linked device = "my MAC 1"
linked device = "my Droid 1"
etc...
Though you can (which caused my confusion), you typically should not set a different "user name" for each device on which you install Resilio Sync.
I believe the two degrees of freedom, e.g. user name and device name, per install will confuse others and suggest some better documentation. Apologies if documentation already exists and I was missed it.
My One Cent,
