By default, you can only install apps downloaded from Google Play. The Security menu lets you allow installation of non-Play Store apps on your phone.
To allow installation of non-Play Store apps on the phone:
- Tap > > Settings.
- Tap Security.
- Select the Unknown sources option.
Important: After installing the app, go back to Settings > Security and make sure to clear the Unknown sources option. This can help protect your phone from installing other insecure apps from the Web.