Import AJAX problem. Please, try import data manually.

And we just noticed that your site shows the error “Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 786432 bytes) in /home/staydigital/public_html/olsa/wp-content/plugins/revslider/includes/googlefonts.php on line 2410”

It seems that your server has no enough memory limit and you need to increase it and try import data again.

This article may be useful for you https://docs.woothemes.com/document/increasing-the-wordpress-memory-limit/

To create “Mega menu” dropdown you need to create a new HTML block in admin panel with Visual Composer (to enable VC for this post type you need to go to Visual Composer -> Role Manager -> Post Types and choose custom then select all post types). You can set it’s layout as you wish. Here is some example from our demo https://docs.google.com/document/d/1n5NuC2NhENQ6FygLzlyAmDz6nTiFH2ryrQ-4ZjfoRYw/edit?usp=sharing
After that you just copy this block’s shortcode (ex.: [html_block id="20396"]), go to Appearance -> Menus and paste it to the desired menu item’s description field. Also change it’s design to “Set sizes” and change dropdown sizes. Check the screenshot

You just need to check “Description” field to be visible in wordpress “Screen Options” in the right top corner on this page.