Max Mega Menu comes with a built in widget which allows you to display a single menu location within a widget area. Depending on your theme, you might have widget areas set up in the header, footer and sidebar areas. Using the following method we can add a Mega Menu to any of these areas.

If you are using an existing menu location, simply add a Max Mega Menu widget to your widget area and select the relevant menu location.
The following steps assume you want to display a brand new mega menu using a widget.
Step 1: Registering a new menu location.
First we’ll need to create a new menu location specifically for use within the widget.
Under Mega Menu > Menu Locations, click “Add another menu location”, give the new location a suitable name and click “Add menu location”. In our case we’ve named the location “Sidebar”.

We now have a new menu location which we can use within the Max Mega Menu widget.
Tip: Advanced users may prefer to register a new menu location using the register_nav_menu function.
Step 2: Assign a menu to the new location
Under Appearance > Menus, create a new menu and tick the new location under “Menu location” in the Menu Settings (or assign a menu when creating the location in Step 1).

Step 3: Add the Max Mega Menu widget to a sidebar
Under Appearance > Widgets, add the Max Mega Menu widget (not the Navigation Menu widget) to a widget area and select the new menu location.

The menu will now be displayed in your sidebar. You can repeat the same steps to create and display multiple Mega Menus on your site.