There are a number of Setup Actions (privileges) directly related to STEP Workflows, both in terms of allowing users to configure workflows and to work with tasks within workflows. In addition to workflow-specific privileges, workflows also take into account general privileges. For example, if a user does not have access to a specific set of objects or data points, they will not have access to them within a workflow either, unless specific access is granted within the workflow.
For complete information on privileges related specifically to workflows, refer to the Workflows section of the Setup Actions and Error Descriptions topic in the System Setup documentation here.
For information on editing general privileges to provide access to data or objects specifically within a particular workflow state, refer to the Editing Privilege Rules section of the System Setup documentation