Thank you! I was worried you might have gotten ripped off with a fake Samsung device. It happens and the fakes don't have the ability to update.
But the information you posted checks out with the official specs of the device. So that's good!
As for the issue... I searched around a little. I found something similar for a different Samsung device. Someone mentioned that the update option wasn't located in the 'about' section as you'd expect, but it had it's own thing in the settings. Perhaps you can poke around in the settings a little more and see if you spot it somewhere else?
I've never owned a Samsung so I'm not super familiar with the way they lay out their menus. I'm about to head to bed but I will do a little more searching tomorrow and see if I can find anything.
Let me know if you end up finding the update option somewhere else in the settings.