I've got a .NET Web API project using Windows Authentication. In my development environment, I can't do a successful POST request with data from my Angular app. It returns:

OPTIONS http://localhost:9090/api/values 401 (Unauthorized)
Failed to load http://localhost:9090/api/values: Response for preflight has invalid HTTP status code 401.

I've tried all means of implementing cors with Microsoft.AspNet.WebApi.Cors to no avail. But currently I've removed the Microsoft.AspNet.WebApi.Cors package from my project in favor of the web.config method (if I actually still need Microsoft.AspNet.WebApi.Cors installed to do the following in Web.config, plz let me know):

Web.config:

.NET Web API 'ValuesController.cs':

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web.Http;

namespace api.Controllers
{
    [Authorize]
    public class ValuesController : ApiController
    {
        // GET api/values
        public IEnumerable Get()
        {
            return new string[] { "value1", "value2" };
        }

        // GET api/values/5
        public string Get(int id)
        {
            return "value";
        }

        // POST api/values
        public void Post([FromBody]string value)
        {
        }

        // PUT api/values/5
        public void Put(int id, [FromBody]string value)
        {
        }

        // DELETE api/values/5
        public void Delete(int id)
        {
        }
    }
}

Angular Component (sends data to my Angular service):

  constructor(private myService: MyService) {
    this.myService.myPost({ID: 1, FirstName: 'Bob'})
    .subscribe(
      data => console.warn(data),
      err => console.error(err),
      () => console.log("empty")
    );
  }

Angular Service (posts the component's data to my Web API):

import { Injectable } from '@angular/core';
import { HttpClient, HttpResponse, HttpRequest, HttpHeaders, HttpInterceptor, HttpHandler, HttpEvent, HttpParams} from '@angular/common/http';

import { Observable } from 'rxjs';
import { from } from 'rxjs';
import { map, filter, catchError, mergeMap } from 'rxjs/operators';

@Injectable({
  providedIn: 'root'
})
export class MyService {

  constructor(private http: HttpClient) {

  };


  public myPost(body) {

      const httpOptions = {
         withCredentials: true
      }

      return this.http.post("http://localhost:9090/api/values", body, httpOptions);

  }

}

From my research it seems that perhaps I need to pass in an Authorization header in my request via my httpOptions variable in the service. But I don't know what to pass as the value for the Authorization property. See the question marks below: MyService.ts

  public myPost(body) {
    const httpOptions = {
      headers: new HttpHeaders({
        'Authorization': '?????'
      }),
      withCredentials: true
    }
      return this.http.post("http://localhost:9090/api/values", body, httpOptions);
  }

Maybe this isn't even my problem though. CORS + Windows Authentication - any ideas?