Just want to share some code to make Mega menu 6 Columns.

Add this css code to your divi custom css:

#top-menu li.mega-menu > ul > li:nth-of-type(6n+1) {
clear: left;
}
#top-menu li.mega-menu > ul > li:nth-of-type(4n+1) {
clear: none;
}
#top-menu li.mega-menu > ul > li {
width: 16%;
}

Sent from my Samsung Galaxy smartphone.