update required to activate iPhone

so I just got a new iPhone 7 Plus but when I try to set it up I get a message saying that I need to update it in order to activate it. So I downloaded iTunes for Windows 10 and the phone doesn't have many options to update, but then I tried it a few more times, and then iTunes started saying that I need my SIM pin or I need to restart the phone so I did and nothing changed (This is a carrier unlocked Phone). So my question is how do I update it so I can finish setting it up to use.