My phone won't let me download the APK! What's going on?
If your phone has an older version of Android than 6.0 (Marshmallow), it won't let you download apps from sources other than the Play Store. In order to get around this limitation, all you need to do is enable installation from unknown sources in your phone's Security settings. To do this, go to Settings -> Security and then check the box next to Unknown sources. Then try downloading again.