By default, new users will start out with an empty collection, containing only the “Inbox” (whose name can be changed through the settings).
An empty slate can be overwhelming, so it might be a good idea to start them out with a few example saved recipe collections. You could create an empty saved collection that has the perfect layout for a weekly meal plan, for example. To then have this saved collection show up for new users, enable the “Default” checkbox on the WP Recipe Maker > Manage > Features > Saved Collections page:
Changing the default will only affect collections for new users. Once someone has accessed the collections feature, you can only affect it by editing it directly.