Hello,

Than you very much for choosing our theme and contacting our support.

This menu is made by means of HTML blocks: https://xtemos.com/docs/basel/html-blocks/ which are created by means WP BAkery page builder http://prntscr.com/kue9pq

1. You create HTML block

2. You add HTML ID into menu item as described here: https://xtemos.com/docs/basel/create-menu/

The bottom blocks are also created in HTML and its ID has been added to the Theme Settings > Footer > Pre-footer area

Best Regards