How to Track app downloads in google analytics

I want to get the app Downloads in both versions ios and android in google analytics … I searched a lot but didn’t get declared article or tutorial

“App downloads” is not a measure your actual app can track. It can only come from who controls the downloads, being the App and Play Store. If an app is downloaded but never started, your app is never activated.

If you are looking for “number of apps that were installed on a device and then started at least once”, just track an event in the app on first start (first start = check if a specific value is set in a database or data store, if not present it is first start, then set the value) to Google Analytics.