This feature is only for Enterprise accounts. To duplicate to a new workspace, you must be an Editor or above in the current workspace, and must be able to create a playbook in the new workspace (Participant or above).
To copy a playbook into a different workspace, click the Duplicate button dropdown at the top of the playbooks and select Duplicate into Different Workspace.
After selecting this option, Click the duplicate button (shown below). Identify your target workspace and hit Duplicate. You're done!