Ion Auth create user (not administrator) without login

Well, my question is this, I have implemented a login system using the fantastic Ion Auth library, which brings with it multiple options, including an administrator panel to create administrators, groups or non-administrator users within of those groups. What I want to achieve is that from outside the logeo system I can create users (not administrators) so that users can create their own accounts and enter the application (these users can not access the administrator's functions).

The fact is that when I try to go directly to create a user by calling the function create_user (), it redirects me to the login without letting me create it.

The function

// create a new user
    public function create_user() {
        $this->data['title'] = $this->lang->line('create_user_heading');

        if (!$this->ion_auth->logged_in() || !$this->ion_auth->is_admin()) {
            redirect('auth', 'refresh');
        }

        $tables = $this->config->item('tables', 'ion_auth');
        $identity_column = $this->config->item('identity', 'ion_auth');
        $this->data['identity_column'] = $identity_column;

        // validate form input
        $this->form_validation->set_rules('first_name', $this->lang->line('create_user_validation_fname_label'), 'required');
        $this->form_validation->set_rules('last_name', $this->lang->line('create_user_validation_lname_label'), 'required');
        if ($identity_column !== 'email') {
            $this->form_validation->set_rules('identity', $this->lang->line('create_user_validation_identity_label'), 'required|is_unique[' . $tables['users'] . '.' . $identity_column . ']');
            $this->form_validation->set_rules('email', $this->lang->line('create_user_validation_email_label'), 'required|valid_email');
        } else {
            $this->form_validation->set_rules('email', $this->lang->line('create_user_validation_email_label'), 'required|valid_email|is_unique[' . $tables['users'] . '.email]');
        }
        $this->form_validation->set_rules('phone', $this->lang->line('create_user_validation_phone_label'), 'trim');
        $this->form_validation->set_rules('company', $this->lang->line('create_user_validation_company_label'), 'trim');
        $this->form_validation->set_rules('password', $this->lang->line('create_user_validation_password_label'), 'required|min_length[' . $this->config->item('min_password_length', 'ion_auth') . ']|max_length[' . $this->config->item('max_password_length', 'ion_auth') . ']|matches[password_confirm]');
        $this->form_validation->set_rules('password_confirm', $this->lang->line('create_user_validation_password_confirm_label'), 'required');

        if ($this->form_validation->run() == true) {
            $email = strtolower($this->input->post('email'));
            $identity = ($identity_column === 'email') ? $email : $this->input->post('identity');
            $password = $this->input->post('password');

            $additional_data = array(
                'first_name' => $this->input->post('first_name'),
                'last_name' => $this->input->post('last_name'),
                'company' => $this->input->post('company'),
                'phone' => $this->input->post('phone'),
            );
        }
        if ($this->form_validation->run() == true && $this->ion_auth->register($identity, $password, $email, $additional_data)) {
            // check to see if we are creating the user
            // redirect them back to the admin page
            $this->session->set_flashdata('message', $this->ion_auth->messages());
            redirect("auth", 'refresh');
        } else {
            // display the create user form
            // set the flash data error message if there is one
            $this->data['message'] = (validation_errors() ? validation_errors() : ($this->ion_auth->errors() ? $this->ion_auth->errors() : $this->session->flashdata('message')));

            $this->data['first_name'] = array(
                'name' => 'first_name',
                'id' => 'first_name',
                'type' => 'text',
                'value' => $this->form_validation->set_value('first_name'),
            );
            $this->data['last_name'] = array(
                'name' => 'last_name',
                'id' => 'last_name',
                'type' => 'text',
                'value' => $this->form_validation->set_value('last_name'),
            );
            $this->data['identity'] = array(
                'name' => 'identity',
                'id' => 'identity',
                'type' => 'text',
                'value' => $this->form_validation->set_value('identity'),
            );
            $this->data['email'] = array(
                'name' => 'email',
                'id' => 'email',
                'type' => 'text',
                'value' => $this->form_validation->set_value('email'),
            );
            $this->data['company'] = array(
                'name' => 'company',
                'id' => 'company',
                'type' => 'text',
                'value' => $this->form_validation->set_value('company'),
            );
            $this->data['phone'] = array(
                'name' => 'phone',
                'id' => 'phone',
                'type' => 'text',
                'value' => $this->form_validation->set_value('phone'),
            );
            $this->data['password'] = array(
                'name' => 'password',
                'id' => 'password',
                'type' => 'password',
                'value' => $this->form_validation->set_value('password'),
            );
            $this->data['password_confirm'] = array(
                'name' => 'password_confirm',
                'id' => 'password_confirm',
                'type' => 'password',
                'value' => $this->form_validation->set_value('password_confirm'),
            );

            $this->_render_page('auth/create_user', $this->data);
        }
    }