The TukOut app is recommended for smartphones and tablets. What device are you using?
The installation happens here, not on the Google Play Store.
Tap the button next to the address field in the browser and select "Add to Home screen" in the list of options that appears.
The installation happens here, not on the App Store.
Tap the button in the browser. Scroll right among the options that appear and select "Add to Home Screen".
Due to iOS limitations, Facebook sign-in is currently not available in the TukOut app on iOS devices.