Appearance >> menu >> footer Menu
There’s no “Footer” on the menu location list on Appearance > Menu but we can still put the menu you’ve created on the Footer through a widget.
Go to Appearance > Widgets. Go to either Footer bar or Footer Widget areas and add “Navigation Menu” on it.
Once you’ve added the navigation menu widget, it will show a dropdown that will let you pick from the existing menus on your site. You should find “Footer menu” you’ve created on the dropdown list. Select it so it would display on the footer widget area you’ve placed it on.
See this demo video for visual example on how to do it – https://share.getcloudapp.com/rRubWXrd