For GOOGLE

—  Go to the Google Play Store on your computer or mobile phone.
—  Type the name of your app in the search.

—  Copy the download URL link.

For APPLE

For your white label apple app download link, you can find this by typing your app name in the App Store search.

If your app has recently been launched, it may not be shown on the app store yet. If this is the case, you can then find your link by 

—  Log in to your app store connect account.
—  Click My Apps. 

—  Click on your app.

—  Click View on App Store.

— Copy the download URL link.