The Rooms Listing page will be auto-generated after you create room pages and it will list them in a column.
Go to Appearance > Customize > Rooms Settings > Rooms Link Slug to see the link for the Rooms Listing page.
The default slug of the page is Rooms. If you decide to change it, it is possible that you will have to reset the Permalinks for the change to take effect.
To reset, go at Settings > Permalinks, select a different option for Common Settings and save the changes. After this, select your initial option and save it. This will reset the Permalinks and the URL of your new listing page should work fine.