Downloading HTML file to open instead of installing Kodi?

For some reason I’m struggling to down load kodi onto my firestick. I’ve followed all instructions, after going to kodi.tv/download and scrolling to the android icon as per the instructional video I’ve watched, when I click the ‘ARM’ it should download then ask me if I want to install Kodi. What I actually get is no response at all, or a very small file which asks if I want to open in amazon HTML viewer or ES Explorer viewer.
I must be missing something surely?