There is another grouping method for your listings, using collections. It is very simple and easy to use. The collections are using a standard WordPress custom post type.
How to create a collection?
Login to your admin dashboard, then navigate to Listing Types Collections, and here you will find all your available collections. If you edit (or create) one collection, you will find additional options like Tags, which allows you to make some basic relations between your collections and listings.
There is another option: Listings, which will display all the attached listings to that specific collection.
Attaching your listings to any specific collection
There is another way to attach your listings to a collection. You can create a new custom field for collection inside your listing fields, by going to Listing Types (edit any listing type) Listing Fields, then use the module drop-down and add Collection field. Now you will be able to define the listing collection through the submission process.
Create a page to display all the available collections
If you need such a page, simply navigate to Pages Add New and create a blank page, just name it properly. Then go to Listing Types Settings General Pages, and use the Collections page options to select that same page you have just created. Learn more about pages.