“wpc_after_receiver_details_metabox” is an action that allows you to add custom fields in the receiver details section.

Copy and paste the following code in your current theme’s function.php

function my_custom_receiver_meta($post_ID){ ?>
    <tr>
    <th><label>
        <?php esc_html_e('Company Name','wpcargo'); ?>
      </label></th>
    <td><input type="text" id="wpcargo_company_name" name="wpcargo_company_name" value="<?php echo esc_html( get_post_meta($post_ID, 'wpcargo_company_name', true) ); ?>"size="25" /></td>
  </tr>
  <tr>
    <?php
}

add_action( 'wpc_after_receiver_details_metabox', 'my_custom_receiver_meta', 99 );

Screenshot: