How to make a code component that works with DataProvider?

According to this page, having a container code component surrounding its children with the Plasmic DataProvider (@plasmicapp/host) context should make the value of the data property of the latter available to each of its children in the Data Picker interface (dynamic value context). I did exactly as instructed, but no data appears in the Data Picker. My local Plasmic Host is up and running, everything else about my code components work fine, except the DataProvider part. Is it a premium functionality? Thanks.