1. About Unknown Sources
Android protects users from inadvertent download and install of Apps from locations other than Google Play (which is trusted). It blocks such installs until the user opts-in Unknown sources in settings. To allow the installation of Apps from other sources, users need to enable the Unknown sources setting on their devices.
2. Reason to enable Unknown Sources
Under WiFi connection, you may fail to install Apps downloaded from Mobo. In this case, you can enable Unknown Sources and then retry to install the Apps.
3. Steps to enable Unknown Sources
1) Tap Settings on your device.
2) Tap Security.
3) Tap Unknown sources.
4) Tap Ok on the pop-up Attention.
5) Now you can see the Unknown sources has been enabled.