Drones in Australia

Sourced a Vankyo S7 7" tablet through Amazon, $79AU plus postage. Thought I might be onto something. Android 9 Pie, quad-core 64 bit processor. DJI Fly app not available on Google Play store so side loaded successfully but refused to install. Tried DJI Go 4 download and installation. Worked fine. What is wrong with DJI? Why do they impose so many restrictions and deficiencies with the Fly app, or more specifically the Mavic Mini