The data export feature for the ROOKIE (free) plan is available on app credits basis. 

You can learn more about our plans and the app credits here ;)

First, go to the app section of your Shopify admin panel: 

and select our awesome app:

Next, go to "Bulk actions -> Export": 

Once there, you can select the resource type you'd like to export to a CSV file from a drop-down menu:

We're almost done! The final step is to decide whether you'd like to export all metafields for a given resource type or a filtered selections of metafields. In case you want to export metafields within a specific namespace and/or key only, you have to fill in the corresponding fields:

otherwise, leave them empty and proceed with the data export.

That's all :)