var request = new HttpRequestMessage(HttpMethod.Get, "Login/EnrollUser");
        var payload = Newtonsoft.Json.JsonConvert.SerializeObject(uec);
        HttpContent c = new StringContent(payload, System.Text.Encoding.UTF8, "application/json");
        request.Content = c;

        var response = await client.SendAsync(request);
        response.EnsureSuccessStatusCode();

[Route("API/[controller]")]
    [ApiController]
    public class LoginController : ControllerBase
...

[HttpGet("{a}")]
        public void EnrollUser(Classes.UserEnrollmentClass a)
        {
            string s = "hjhjhj";
        }