On Android device, navigate to 'Apps' > 'Settings' > 'Security', enable 'Unknown Sources', then tap 'OK' to agree to enable this setting. This will allow the installation of third party apps and standalone APKs.

The easiest way to install an APK file on your Android is to download the file using the default browser, Chrome. Find a website offering the Android app and tap the link to download the APK file. Accept any pop-ups, including This type of file can harm your device.  Only download APK files from reputable sources.