Document Understanding Process - New Studio Template

In order to run this attended, do I need to set the ‘-Attended’ workflow as Main?

I tried to run the project as-in without making any changes, and I get the error:
An extension of type ‘UiPath.Activities.Contracts.Persistence.IPersistenceBookmarks’ must be configured in order to run this workflow.
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According to this reply on a related thread, I assume I must be doing something wrong when trying to run it in attended mode.