1. Open your Android's Settings.
2. Scroll down and tap Apps and notifications.
[On a Samsung Galaxy, you'll instead tap Biometrics and security.]
3. Tap Install unknown apps.
[On some Androids, you may first have to tap Special access.]
4. Select a browser. Tap the browser you want to use to download your APK files. [For example, Google Chrome.]
5. Tap the white "Allow from this source" switch.
[On some Androids, you may instead need to tap an "Allow from this source" checkbox.]
6. Tap OK if prompted.
7. Enable APK installation for your Android's file manager.
8. Click Download on this website.
9. Tap OK when prompted.
10. Tap OPEN when prompted. [If you miss the OPEN notification, you can instead swipe down from the top of the screen and tap the Download complete (or similar) notification.]
11. Tap INSTALL.
12. Open and Enjoy the App.
13. Disable again Installations from Unknown sources to protect your phone following Step 1.