^^&&^^

Edit File: multi-select.php

<?php
namespace Elementor;
defined( 'ABSPATH' ) || exit;

Class MetForm_Input_Multi_Select extends Widget_Base{

use \MetForm\Traits\Common_Controls;
    use \MetForm\Traits\Conditional_Controls;
    use \MetForm\Widgets\Widget_Notice;
    use \MetForm\Traits\Quiz_Control;

public function get_name() {
		return 'mf-multi-select';
    }
    
	public function get_title() {
		return esc_html__( 'Multi Select', 'metform' );
    }

public function show_in_panel() {
        return 'metform-form' == get_post_type();
    }
    
    public function get_categories() {
		return [ 'metform' ];
    }
    
	public function get_keywords() {
        return ['metform', 'input', 'select', 'multi select', 'dropdown', 'multiple dropdown'];
    }

protected function register_controls() {

if ( $this->get_form_type() == 'quiz-form' && class_exists('\MetForm_Pro\Base\Package') ) {
			$this->start_controls_section(
				'quiz_section',
				[
					'tab' => Controls_Manager::TAB_CONTENT,
					'label' => esc_html__( 'Content', 'metform' ),
				]
			);

$this->quiz_controls(['multi-select']);

} else {
            $this->start_controls_section(
                'content_section',
                [
                    'label' => esc_html__( 'Content', 'metform' ),
                    'tab' => Controls_Manager::TAB_CONTENT,
                ]
            );

$this->input_content_controls();

$input_fields = new Repeater();

$input_fields->add_control(
                'label', [
                    'label' => esc_html__( 'Input Field Text', 'metform' ),
                    'type' => Controls_Manager::TEXT,
                    'default' => esc_html__( 'Input Text' , 'metform' ),
                    'label_block' => true,
                    'description' => esc_html__('Select list text that will be show to user.', 'metform'),
                ]
            );
            $input_fields->add_control(
                'value', [
                    'label' => esc_html__( 'Input Field Value', 'metform' ),
                    'type' => Controls_Manager::TEXT,
                    'default' => esc_html__( 'Input Value' , 'metform' ),
                    'label_block' => true,
                    'description' => esc_html__('Select list value that will be store/mail to desired person.', 'metform'),
                ]
            );

$input_fields->add_control(
                'mf_input_option_status', [
                    'label' => esc_html__( 'Status', 'metform' ),
                    'type' => Controls_Manager::SELECT,
                    'default' => '',
                    'options' => [
                        '' => esc_html__( 'Enable', 'metform' ),
                        'disabled'  => esc_html__( 'Disable', 'metform' ),
                    ],
                    'description' => esc_html__('Want to make a option? which user can see the option but can\'t select it. make it disable.', 'metform'),
                ]
            );

$input_fields->add_control(
                'mf_input_option_selected', [
                    'label' => esc_html__( 'Select it default ? ', 'metform' ),
                    'type' => Controls_Manager::SELECT,
                    'default' => '',
                    'options' => [
                        'selected' => esc_html__( 'Yes', 'metform' ),
                        ''  => esc_html__( 'No', 'metform' ),
                    ],
                    'description' => esc_html__('Make this option default selected', 'metform'),
                ]
            );

$this->add_control(
                'mf_input_list',
                [
                    'label' => esc_html__( 'Multi Select List', 'metform' ),
                    'type' => Controls_Manager::REPEATER,
                    'fields' => $input_fields->get_controls(),
                    'title_field' => '{{{ label }}}',
                    'default' => [
                        [
                            'label' => 'Item 1',
                            'value' => 'value-1',
                            'mf_input_option_status' => '',
                        ],
                        [
                            'label' => 'Item 2',
                            'value' => 'value-2',
                            'mf_input_option_status' => '',
                        ],
                        [
                            'label' => 'Item 3',
                            'value' => 'value-3',
                            'mf_input_option_status' => '',
                        ],
                    ],
                    'description' => esc_html__('You can add/edit here your selector options.', 'metform'),
                'frontend_available' => true,
                ]
            );
        }