The first level menu needs to have CSS class pmcbig. After that you set up the 4 columns (first level sub menu), they need to have CSS class set to pmcmenutitle. Now you can add menu items to the second level (in our case there is 5 items in each column). The second image demonstrate how to set them up. If you want to add font awesome icons be sure to fill the proper label. There is a link which will lead you to the list of all the icons that can be used.
If CSS Class is hiden check this screen: