How to login to Spotify using Vue + Express?

Question

OAuth

I'm trying to implement authorization for the Spotify service according to their guideline . Implemented something like this:
1. On the client side (Vue) through axios I make a request to the server (Express).

2. On the server, I repeat everything in the same way as in the example

. In theory, there should be a redirect to the auth spotify page, but in the end I get the following error:

Here is info from the network

First, because of which I have a problem with cors, if I follow the example and there is no such problem in the example?
Secondly, how to fix it? I tried to prescribe headers through res.header () before the redirect, but it did not help.