Once npm finished installing and you have downloaded the client on your phone, run the expo start command. This will start up the app and it should boot up in your web browser. Use your camera/QR code scanner to scan the QR code and open the app on your mobile device.
If you get an error when trying to open on your phone about "unable to resolve @expo/vector-icons" let me know
In your favorite IDE, you can start making changes to the app. The best place to start is AnxietyApp/screens/HomeScreen.js
Save the file and watch the screen update in real time!