The chat app project was created with React-Native app using Expo Cli.
You will also need a Firebase Account. Firebase is Google's mobile platform that helps you quickly develop high-quality apps
For this project, I use npm install & expo install.
You can use yarn or npm to install all the required libraries. It is a matter of personal choice, but both have their advantages.
The expo install will install compatible dependencies that works with your current setup.
npm install will look for the latest dependency library the output might cause your App not to work properly.
Read more at Difference expo install versus npm install
To install dependecies run: npm install or npm i
To start the app run: expo start