Answer
https://stackoverflow.com/questions/70446257/cannot-find-module-using-yarn-v-3/70446622#70446622
I figure out that the problem is that I have to run index.js using this command:
$ yarn node index.js
15
As I understand it uses PnP to resolve dependencies:
https://yarnpkg.com/features/pnp
https://yarnpkg.com/features/pnp#initializing-pnp
Problem
I will do step by step installation of yarn from here https://yarnpkg.com/getting-started/install