Head over to the URL below (or use the course links page) and use it to clone the starting project in Xcode.

https://github.com/appbrewery/Calculator-Advanced-Swift-iOS13

Simply clone the project from Github using Source Control → Clone inside Xcode. If you need a refresher on cloning repos, have a look at this lesson from the Dicee module: https://www.udemy.com/ios-13-app-development-bootcamp/learn/lecture/16251580/#overview