Hello,
Unfortunately, our theme does not have 3 levels mega menu. Conditional Menus allows to show different menus for the different pages, it’s not build the mega menus, isn’t it?
If you just need to show the different menus for the different pages or categories you can use multiple headers option https://youtu.be/BpeXfzNwkOc
But if you need 3levels mega menu then you should look for some plugins for the mega menus that allow the creation of such mega menus.
Regards