To navigate your way through applications built with Create React App & perform common tasks visit the official guide here.
If end to end tests are failing make sure the server is running in the background. You may also try rebuilding puppeteer
> npm rebuild puppeteer --force
This will redownload chromium.
Not Familiar with Git?
You can just download the .zip file. Extract the contents, then move to the project directory, open your terminal, and use:
> npm install > npm run dev
Those who are not yet familiar with Git but want to learn more about how to use it, check out these resources to dive into git workflow -