Heres the correct web.config entry...

  <location path="exampleUrl">
    <system.web>
      <authentication mode="None" />
      <authorization>
        <allow users="*"/>
      </authorization>
      <customErrors mode="Off"></customErrors>
    </system.web>
 </location>

Solved it like this.

protected void Application_BeginRequest()
{
     var startUrl = "/exampleUrl";
     if(Request.Url.AbsolutePath.StartsWith(startUrl))
     {
         Response.SuppressFormsAuthenticationRedirect = true;
     }
}