Navigate to the folder where you downloaded Gravity and open the /config/default.json. Next, add your database and Mailgun credentials.
The Expo CLI will enable you to perform a variety of Expo tasks, like running and building your app.
npm install --global expo-cli
On your iOS or Android mobile device, visit the respective app store and download the Expo mobile client then register a free account.
npm run setup
This will install all of the dependencies required and start your app. If you open the Expo mobile app or iOS or Android simulator, you'll be able to see your app.
Finally, to run your app any time, enter the following command.
npm run dev
This will start both Gravity Server and the Expo client.
Once your Expo server is running, you can open your app in the Android similar by pressing a or i to open the iOS simulator.