Auto Routing (improved) post method not working

I'm using Auto Routing (Improved) and have set $autoRoute option to true in app/Config/Routing.php

and

$autoRoutesImproved to true in app/Config/Feature.php


I have created a Controller: Auth

class Auth extends BaseController
{
    public function postLoginUser()
    {
        var_dump($this->request->getPost());
        exit;
    }
}

I am posting data using HTML form to url = auth/loginUser

<form id="frmLogin" accept-charset="UTF-8" method="post" action="<?php echo get_url("auth/loginUser") ?>"
      role="form" data-parsley-validate>
    <input class="form-control form-control-border border-width-2 form-control-lg" placeholder="E-mail"
          title="Enter E-mail" name="email"
          id="email" data-parsley-trigger="change" required="" type="email">
    <input class="form-control form-control-border border-width-2 form-control-lg" placeholder="Password"
          title="Enter Password"
          name="password" type="password" value="" required>
    <button id='submit' type="submit" class="btn btn-lg btn-primary btn-block btn-flat">Submit</button>
</form>


On submit this form I'm getting error:
404
Controller or its method is not found: \App\Controllers\Auth::getLoginUser


Can anyone help me sort this issue?