Set cookie for non-native integration submit or link click.

om-set-cookie.js

jQuery(document).ready(function($){
    // Replace #my-submit-button with the specific class or ID of the submit button or link
    $('#my-submit-button').on('click', function(event){
      // Replace ld9sda3fdwy4 with your specific optin's slug
      $('html div#om-ld9sda3fdwy4 .om-close').trigger('click');
    });
});