To displaying flyout offCanvas & mobile menu, you need to add offCanvas/Mobile Menu trigger from elementor widget.
To change the layout and others settings, go to the options at Theme Options ->General -> OffCanvas & Mobile Menu and you will find all the relevant options.
Mobile devices are completely different to desktops, therefore the menu set to it should be different to the desktop menu. For this reason this theme allows you to create/set a specific menu for mobile device.
Log into your site backend
Go to Appearance -> Menus
If you don't already have menus created, set a new one up
In the Menu Settings section below set this menu to Display in the Mobile Menu location.