How do I set up Apple TV on fire tv

You would download the Apple TV app from the Amazon Fire TV Apps & Games Store, if your model device and region are supported. If your Fire TV supports Alexa, then you can even ask “Alexa, find the Apple TV app”.

Once you have the Apple TV app installed, you would have to sign in with your Apple ID account.

Apple TV app user guide for smart TVs and third party streaming devices - Apple Support

Apple TV App–Supported Devices

• Amazon Fire TV Stick 4K (2018)
• Amazon Fire TV Stick – Gen 2 (2016)
• Amazon Fire TV Stick – Basic Edition (2017)
• Fire TV Cube (Gen 2)
• Fire TV Cube (Gen 1)
• Fire TV – Gen 3 (2017)
• Nebula Soundbar – Fire TV Edition
• Fire TV Edition – Insignia HD (2018)
• Fire TV Edition – Insignia 4K (2018)
• Fire TV Edition – Toshiba 4K (2018)
• Fire TV Edition – Toshiba HD (2018)