Wordpress [ LearnPress ] how to add a Checkbox into one of course tabs

i had already made a plugin to allow admins to approve or deny student's enroll before purchase, but i'm stuck now with no experience in WP to add a checkbox allowing admins to use this option into the course settings, i tried to check all Learnpress files through Plugins Editor, i found this function lp_meta_box_checkbox_field under learnpress/inc/admin/views/meta-boxes/class-lp-meta-box.php then i tried to add another field into the price.php file, but with no chance

here is my learnpress/inc/admin/views/meta-boxes/course/tabs/price.php:

<?php
/**
 * Course price data panel.
 *
 * @author ThimPress <nhamdv>
 */

defined( 'ABSPATH' ) || exit;

$payment = get_post_meta( $thepostid, '_lp_payment', true );
?>

<div id="price_course_data" class="lp-meta-box-course-panels">

    <?php if ( current_user_can( LP_TEACHER_ROLE ) || current_user_can( 'administrator' ) ) { ?>
        <?php
echo "TEST";
    
        $message    = '';
        $price      = get_post_meta( $thepostid, '_lp_price', true );
        $req_approve = get_post_meta( $thepostid, '_lp_apporve_request', true );
        $sale_price = '';
        $start_date = '';
        $end_date   = '';

        if ( $payment != 'free' ) {
            $sale_price = get_post_meta( $thepostid, '_lp_sale_price', true );
            $start_date = get_post_meta( $thepostid, '_lp_sale_start', true );
            $end_date   = get_post_meta( $thepostid, '_lp_sale_end', true );
        }
    //MY CUSTOM FIELD
            lp_meta_box_checkbox_field(
            array(
                'id'                => '_lp_approve_request',
                'label'             => esc_html__( 'Enroll requesst', 'lp-enroll-request' ),
                'description'       => 'choose wether if you want students to enroll directly or ask admin permission firstly.',
                'default'           => $req_approve,
                'name'              => 'enroll-request',
                'class'             => 'lp_meta_box_enroll_request',
            )
        );
///ENDS HERE
        do_action( 'learnpress/course-settings/before-price' );

        lp_meta_box_text_input_field(
            array(
                'id'                => '_lp_price',
                'label'             => esc_html__( 'Regular price', 'learnpress' ),
                'description'       => sprintf( __( 'Set a regular price (<strong>%s</strong>). Leave it blank for <strong>Free</strong>.', 'learnpress' ), learn_press_get_currency() ),
                'type'              => 'number',
                'default'           => $price,
                'custom_attributes' => array(
                    'min'  => '0',
                    'step' => '0.01',
                ),
                'style'             => 'width: 80px;',
                'class'             => 'lp_meta_box_regular_price',
            )
        );

        lp_meta_box_text_input_field(
            array(
                'id'                => '_lp_sale_price',
                'label'             => esc_html__( 'Sale price', 'learnpress' ),
                'description'       => '<a href="#" class="lp_sale_price_schedule">' . esc_html__( 'Schedule', 'learnpress' ) . '</a>',
                'type'              => 'number',
                'default'           => $sale_price,
                'custom_attributes' => array(
                    'min'  => '0',
                    'step' => '0.01',
                ),
                'style'             => 'width: 80px;',
                'class'             => 'lp_meta_box_sale_price',
            )
        );
        ?>

        <div class="lp_sale_dates_fields">
            <p class="form-field lp_sale_start_dates_fields">
                <label for="_lp_sale_start"><?php esc_html_e( 'Sale start dates', 'learnpress' ); ?></label>
                <input type="text" class="short" name="_lp_sale_start" id="_lp_sale_start" value="<?php echo esc_attr( $start_date ); ?>" placeholder="<?php echo esc_html( _x( 'From&hellip;', 'placeholder', 'learnpress' ) ); ?>" style="width:320px;" />
            </p>
            <p class="form-field lp_sale_end_dates_fields">
                <label for="_lp_sale_start"><?php esc_html_e( 'Sale end dates', 'learnpress' ); ?></label>
                <input type="text" class="short" name="_lp_sale_end" id="_lp_sale_end" value="<?php echo esc_attr( $end_date ); ?>" placeholder="<?php echo esc_html( _x( 'To&hellip;', 'placeholder', 'learnpress' ) ); ?>" style="width:320px;" />
                <a href="#" class="description lp_cancel_sale_schedule"><?php esc_html_e( 'Cancel', 'learnpress' ); ?></a>
            </p>
        </div>

        <?php do_action( 'learnpress/course-settings/after-price' ); ?>

    <?php } else { ?>
        <p><?php esc_html_e( 'Price set by admin', 'learnpress' ); ?></p>
    <?php } ?>
</div>

    

and here is where exactly to add my checkbox

please if there is any ideas, or how to go through that?

regards,