To use expo, refer to the Expo Documentation Installation page on the Expo website.
Use npm install -g expo-cli or yarn add expo-cli --global. Start the app by using npm start or yarn start.
To use firebase, refer to Google's Firebase documentation page on the Firebase website.
Create a Firebase account
Login to your account
Create a database
Create and name a collection in your database
Input your user credentials
Click on "authentication" -> "set up sign-in method" -> enable anonymous authentication
Set up cloud storage (click "storage")
Click gear icon above Develop tab -> select "project settings" -> add Firebase to a web app -> copy the firebaseConfig settings and paste into your Chat.js file.