React Native Android/app/build.gradle File Missing

I'm new to react native and I would like to create a simple app working with firebase push notifications. So I've created my react app using 'expo init' Now I'm stuck at point 2 of

Solution 1:

In Expo you have a 'managed' vs. 'bare' workflow (https://docs.expo.io/versions/v34.0.0/introduction/managed-vs-bare/)

If you want to edit the gradle file you'll need to eject to a bare workflow:

Unlike in the managed workflow where you don't touch the underlying native code directly, in this workflow the developer has complete control, along with the complexity that comes with that.

If I remember correctly, you can use the CLI tools and just type 'expo eject'. The Android folder and all project files will then be created.