This video will show you the easiest way to download Kodi to your Amazon Fire TV device (including the Fire TV Stick, Fire TV Stick Lite, Fire TV Stick 4k, Fire TV Cube, and all others). Full text tutorial: https://techmogulchannel.com/tutorial-how-to-install-kodi-to-amazon-fire-tv-stick/
UPDATE: Please download the 32-bit version of Kodi regardless of which Fire TV device you are using (1:42 mark in the video). If you try to install the 64-bit version, you will get an