Hi @aatmaja,
Not sure if this will help, but if you’re just going against a local server, you shouldnt need to refer to it as a proxy, just simply make the request to the localhost / local IP with the port number and url.
As for the authentication side of things, thats where I am not sure. If you do have Basic Authorization set up on your server, then you would include that in the header of the request, and not in the proxy. This should only come into play after you can get some sort of response from the server for any attempt to send it a request.
Other than that, its hard to be sure with out seeing any log information.
Hope this helps!