INSTALLING NON-PLAYSTORE APPS
To allow a non-Playstore app to be installed you should set your device to allow instalation of apps from unknown sources.

HOW TO INSTALL THE APP:
-
Download the app and Double-tap it to install it.
IF IT REFUSES TO INSTALL...
- Open SETTINGS and then tap SECURITY.
- Tap option: UNKNOWN SOURCES to ‘check’ it.
Nature   ExplorerNature   Explorer
Android
MORE INFORMATION
IS IT SAFE TO MANUALLY INSTALL AN APP?
All apps have the ability to access your device, whether they are from Playstore or not. What matters is the 'Permissions' the app asks for during install.  Make sure the app is not asking for permissions it does not need. Nature Explorer only requires internet access for download of your topics and thereafter works 'offline' and without internet.
Topics Download Page
CAN I MANUALLY DOWNLOAD MY TOPICS?
If you have no internet connection you can download one or more nature topics manually.
Follow the instructions on the Topics page. (Click here to visit the manual topics download page.)
Manual downloading of topics is not recommended unless you are familiar with using your Android filing system.

The best method to get nature topics is via the  app's automatic process but WiFi is recommended.