ynaeht,
In the tutorial Section 4.2 Creating CustomersResource Class screenshot 2, you need to select ‘Singleton’ for Lifecycle.
The import will automatically be added basing on the Lifecycle selected and you do not need to explicitly download it and add to the library.
I followed the steps in the tutorial to the tee and could run the example without any issues. I suggest you give it a try again.
let me know how this works for you.