Download the “SFFILM” app on your Apple TV. Once you are in the Apple TV app, you will see an option to sign in as a passholder. Click on that, and you can “pair” your TV with your computer using by navigating to www.watch.sffilm.org/pair and signing in using your credentials, or sign in directly on the Apple TV app.
FAQs > How do I pair my Apple TV app with my passholder login?