Official apps are provided by licensed government or state operators and allow for actual ticket purchases. The Lott (Australia) : The official app for Saturday Lotto (a 6-number draw), Powerball, and Oz Lotto.
Google Play has strict rules for gambling apps. They are usually only available in specific countries or states (like the UK, Ireland, France, and certain US states) where online lottery is legal. 6 lottery app download play store