By default, Android blocks the installation of apps that aren't downloaded from the Google Play store.
If a device does not have access to Google Play, you will need to allow installations from "Unknown Sources."
Enable the "Unknown Sources" option (Android 4.0 and higher)
If you get the "Install blocked" message when you try to install OverDrive for Android, tap Settings. (If you do this, skip to step 3.)
Otherwise, go to your device's Settings by dragging down from the top of the screen and selecting .
- Tap Security (under "Personal").
- Turn on Unknown Sources.
Review the "Unknown sources" message. Tap OK to continue.
- You can now continue installing OverDrive for Android (follow the steps in "Option 2").