Here are the steps to activate USA network on Amazon Fire TV:-
1. The initial step is to turn on your Fire TV and then go to the channel section.
2. Then on the next step search for the USA Network app.
3. Now select the app and then download and install it on your device.
4. Then note the activation code on your display.
5. Now use another device and then visit usanetwork.com/activatenbcu.
6. Then finally enter the code in the space available and click on the Continue button.