Go to the Web URL provided (preferably from the Android mobile device on which you wish to install the app) to get the app installer(apk).
Download it into your phone. You will get a popup warning that this file could be potentially harmful. This is a standard warning. Click “OK” to download the file.
Go to your “Downloads” folder in Android and click on the downloaded file. The screen will warn that you are installing a non-play store app. It might ask you to enable installation of apps from unknown sources. Tick mark this in settings as shown in screenshot.
You will get a screen with app installation permissions as shown below. Click “Install” and you have the app on your Android phone.