After you download the app via the link slide down your notification bar and click on the downloaded file “agc.apk”
A warning as shown will pop-up. Click on “Settings”. (The app is perfectly safe. Since the source of the app is not the Google Play Store, it will warn you)
After you click on “Settings” the phone will directly bring you the the right menu. Click on the slider as shown
When you activate the slider, a pop-up will ask you if you want to install as shown. Click on “Install” Now the App is installed and can be opened from your App drawer