What model Note 5 and what carrier?
On Verizon for example, you must have a activated SIM card installed and that phone installed as the active phone. On the other hand AT&T, when I was with them, only required a SIM card be installed in the phone and it didn't have to be the active phone and the SIM didn't have to be currently activated.
Also, Verizon has upgraded their Note 5 to 6.0.1 but with the possible exception of AT&T none of the other US carriers have.