Navigate to your device’s Settings, select Security or Applications (depending on device) and check the Unknown Sources box.
We have to do this, because Disconnect is too private and secure for the Play Store, which you can read about here.
Only available for Android 4.0 and higher
Date of most recent update to Disconnect Mobile:
5/5/2015 (version 1.1.1 MD5=e653d91defd298dc2a08fa20c0670211).