Hi. By default desktop submenu opens on hover over. To make it ready for touch you shoul use JS

jQuery basic example

jQuery(function ($) {
  $('.sp-megamenu-parent .sp-has-child').on('touchstart', function(e) {
    e.preventDefault();
    $('.sp-dropdown').css('display', 'block');
  });
});

But keep in mind that in this case you will not be able to follow the link itself. There is a logical conflict. Therefore, the solution should be more global than you think. A separate design of the menu for tablets should be made to assign on touch event to the arrow, but not to the whole link. And this arrow should be large enough for a tap with a finger.

A simpler and best way is do not try to solve this, but just hide the desktop menu at a larger breakpoint than by default (for examole at 1024px) and display the offcanvas menu instead via CSS

Hello Vladimir

Your issue is very common and not actually our product's isssue. Please try Pavel's solution and check if it solves your issue.

Best regards