I sincerely apologise for conversing with myself here, but I found another post. The GitHub authentication given on the explanation for the assignment is different from the solution in the link on the same page, however. Neither bring me to the login page. I don’t know how to find the problem, since my console in codesandbox is showing nothing whatsoever.
It must be the url that is wrong, but I am using the url with which codesandbox opens the window, which is: https://pn3x5.sse.codesandbox.io
and then for the callback