Hello, @antonia,
1) Actually, in the document we added 4 columns just for an example to understand how to set the mega menu nothing else. You can set the columns as per your need based on the menu items you have.
2) Issue resolved now kindly check back to your site after clearing the browser cache. See this image to know how I fix it and the result appears now: https://postimg.cc/zHGWGLK0
Regards 8Themes Team.