*Software shown may differ from yours but the installation is the same*
Firstly, If you have previously downloaded the app before you must delete it first.
Next, Click the app you want to download it should start an .apk file being downloaded.
Then Open your file manager.
Select the internal storage of your device and then locate the downloads folder.
From there you should see the apps apk file.
Click the file, It should prompt you to open your settings to enable unknown sources.
Allow this and then click the back arrow at the top left.
Next select install and wait for it to install.
After the app has installed click open.
Enjoy The App! :)