Can you check the details of the error to determine what element you need ownership of?
First things first, you should NOT be making an entire Workset Editable ("Checking it out" in layman's terms). Element borrowing is the best practice for managing worksharing in Revit.
Second, it sounds like you need to have another user relinquish their elements to central. Then you can get access by Reloading Latest and placing the Zones as needed. Element borrowing will take care of element ownership in the background as you place your Zones.
Hope that Helps,
Kyle B
Revit MEP Product Manager
Kyle Bernhardt
Director
Building Design Strategy
Autodesk, Inc.