How to configure request routing to ApiController in WebForms?

Question

ASP.NET

There is a legacy web application in WebForms (NOT MVC!)
It was necessary to attach an api (WebApiController web service) to it with requests like:
{url}/{api}/{action}
Created a web service inherited from ApiController

public class JobController : ApiController
{
        // GET api/<controller>
        public IEnumerable Get()
        {
            return "Hello, world!";
        }
}

In global.asax I wrote:

RouteTable.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{action}/{params}",
            defaults: new { controller = "Job", action = "get" }

the logic is such that if I go to webapp.com/api
, "Hello, world" should return,
of course, it does not work.
Question - how to properly configure the routing of requests to this service?