Given that Marshmallow has been around for a number of months now, it has taken a while for Sprint Galaxy Note 4 and Note 5 owners to get their hands on the latest flavor. Still, it's good to see that both handsets are being catered to simultaneously, and if you've been eager to test the new features of Android's most recent installment on your Note device, your wait is effectively up.
As aforementioned, the update is around 1.4 gigs in size, so it may take a while to download dependent on the state of your connection. If you haven't already gotten the OTA notification and processed the update, you should navigate through Settings --> About device --> Software update --> Update now. As ever, the update may not be available immediately to all, but if you don't have any joy at the first try, simply wait a little and check again at regular intervals.
source: SamMobile (1), (2)