"The current role does not allow editing documents that are being processed" error is shown when trying to open the document in Project Setup Station.
The document is currently being processed by the workflow, and thus can't be edited manually in Project Setup Station.
The changes to the document processed by workflow can only be done using the Verification Station when it is routed to the Verification or Exception stages. Using the Verification Station you can edit the contents of the document and send it to any other stage.
Please note that a Project Setup Station is a station where projects are created, set up, and debugged only. Project Setup Station is not an actual part of your workflow.