Hi there! I’d be happy to help you activate the Met Opera on Demand app on your Amazon Fire TV. To get started, can you tell me if you've already downloaded the Met Opera on Demand app from the Amazon Appstore on your Fire TV? Also, do you already have a Met Opera on Demand account, or will this be your first time signing up?

Meanwhile, here’s the general process to activate the app:

1. Download and open the Met Opera on Demand app on your Amazon Fire TV.
2. When prompted, sign in to your Met Opera on Demand account with your username and password. If you don’t have an account yet, you can register right there or sign up on the Met Opera website.
3. If you’re starting a new subscription, you can begin a free 7-day trial or subscribe as desired.
4. Once logged in, your Amazon Fire TV should be linked to your Met Opera account automatically, giving you full access.

If you see an activation code on your TV instead of a login screen, you’ll want to go to the Met Opera activation webpage from a computer or phone to enter the code and link the device.

Let me know where you are in this process or the exact screen you are seeing, and I can guide you with more detailed steps!