If the ZipGrade mobile app isn't available through the Google Play Store for you, you will need to download the official APK file to install the app manually.
An APK (Android Package Kit) is a type of file that installs an application for Android. Its purpose is similar to other file types, like EXE files on Windows and PKG files on Macs. If you've ever installed an Android app from the Google Play Store, then you've used an APK file without realizing it. (When you tap the Install button, the app store automates the process of transferring the file to your phone and running it for you.)
To install the ZipGrade mobile app from an APK file on an Android device:
Download the APK you want to install. Click this link from your Android mobile device to download the APK file to that device:
https://content.zipgrade.com/apk/ZipGrade-616.apk
Open the downloaded file to begin the installation.
To open the file, tap the completed file download in your device's notifications to start. (Alternatively, you can use the Android device’s file manager, usually called My Files or File Browser in the app drawer, to locate the APK. Note: If there is no file manager app installed yet, you may also need to download a separate, free file manager app from the Google Play Store or your device's app store, such as ES File Explorer.)
You may see an "Open with" prompt with some suggested apps from your device listed. Select the package installer app to complete the installation.
Go into your Settings at the prompt and toggle on Allow from this source.
You can also access this setting from the "Settings" app - search for the "install unknown apps" setting.
Confirm the app installation.
It will ask if you want to install or update the app - confirm and follow the prompts to complete installation.
Once the ZipGrade mobile app has been installed, you can remove the permissions to install unknown apps and the APK file can be deleted.