The Potters Dictionary file is an .apk file and this is an Android App. If you downloaded to a PC, Desktop computer
etc, it doesn't open. You have to move the file to your Android Device.
You could do this with wifi, or using a USB cable from the device to
the PC. The best way is to access the link direct from your Android
Device. Use your email account in the device, or find the web page with
the device. You can also access the app from Google Play.
If you have an iPod, iPhone, unfortunately the update is not yet available on iTunes. The older version on iTunes is flawed. Peter