Amazon Fire OS is a variant of Android. The most important difference from a Bizplay perspective is that it does not come with the Google Play Store from which you can install the Bizplay app. Therefore you have to take a little detour to get your Fire TV setup to automatically play your Bizplay channel. To do so, you need a separate Android device (like a phone or tablet) to transfer the Bizplay app to the Fire TV once.
On the other Android device:
The app should now be transferred to the Fire TV, where you can find it in your apps section and start it. Now you can register the player to have it start playing your Bizplay channel. After this, every time the Fire TV is started, it will automatically start the Bizplay app with the configured channel.
After the installation, you don't need the Bizplay app anymore on your other Android device and we recommend you uninstall it right away to prevent it from automatically starting all the time.