There are no native apps for NightCafe (yet), but you can install the web app directly. Once installed, it behaves exactly as a native app would (no url bar or forward/back buttons, native notifications, etc).

Follow the instructions for your platform to install NightCafe as an app:

Android: Open NightCafe Creator in Chrome, then from the browser menu choose "Install".

iOS: Open NightCafe Creator in Safari, then tap the share button and choose "Add to Home Screen".