Archetype Workbench Setup RM Schema Configuration - No archetypes found

Hello, I’m trying to set up the Archetype Workbench. I installed the openEHR-reference repository by cloning the GitHub repository on my local machine. In the RM Schema Configuration, all schemas are checked by default. But I still get the error message “No archetypes found; may need to enable appropriate RM schema; See RM Schemas > Configure Menu”. Can you please tell me what is missing? Thanks a lot!