Cannot deserialize the current json object because(e.g.{"name":"value"}) into type because the type requires a json array (e.g.[1, 2, 3])

Cannot deserialize the current json object because(e.g.{"name":"value"}) into type because the type requires a json array (e.g.[1,2,3])

{
  "success": 1,
  "login": [
    {
      "username": "123456",
      "password": "123456",
      "store_authority": "Yes",
      "fyear": "2018-19"
    }
  ]
}

string Post_Status = "http://123456.com/webapi/login.php?username=" + username + "&password=" + password + "";
                WebClient webClient = new WebClient();
                webClient.Headers.Add("user-agent", "Only a test!");
                string json = webClient.DownloadString(Post_Status);
                var model = JsonConvert.DeserializeObject<List<RootObject>>(json);

public class RootObject
        {
            public string success { get; set; }
            public List<Login> login { get; set; }
        }

public class Login
        {
            public string username { get; set; }
            public string password { get; set; }		
            public string store_authority { get; set; }		
            public string fyear { get; set; }		
        }