Fastor allow you to create powerful submenu items using Custom Blocks.
First of all you have to enable Custom Blocks in your menus screen options.
- Go to Appearance -> Menus and enable Custom Blocks in Screen options
Go to Custom Block -> Add New
Create your submenu content with Page Builder
Save your custom block and go to Appearance -> Menus.
Edit existing or create new menu
Find your custom block with submenu and add to menu
Set Custom Block in Content type field both for parent and submenu item
Done, check result on front page