Settings > Security > Unknown Sources
Navigate to Security within Settings and enable applications to be installed via unknown sources. Depending on your Android version, you may need to select 'More' tab to view security.
Notifications > IndiaBetPro_2-0-4.apk
Swipe down to view notification centre and select IndiaBetPro_2-0-4.apk. The app will begin to install onto your device. You may have to select the file from your Downloads app to install.
You are now ready to use the app. Open the app to ensure it has installed successfully.