Do you want to use the hamburger menu style for your site? If so, then go to Header Options > Header Style and select this style “Fullscreen Overlay” from the drop-down.
The mobile menu is designed to show up only when a certain screen width has been reached. That includes the mobile screen, portrait and landscape, ipad portrait layout. To change the current desktop menu to mobile requires css customization that is actually not needed knowing that you do have an option to achieve this.
Please try the above first and let us know if it’s ok.
