Access to XMLHttpRequest has been blocked by CORS policy

So I’m running this tutorial:

And at the end there is error request from Angular App to API like this:
Access to XMLHttpRequest at ‘http://localhost:6060/api/messages/public’ from origin ‘http://localhost:4040’ has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.

What else should be set?