MDG supplier change workflow _ WS54300007

Hi All,

I'm working on MDG Supplier Standard CR type (SUPPL2P) and workflow WS54300007 for Supplier change. Where do I add Approver for this Work flow. I added in "Assign Processor to Change Request Step Number" for steps 0,1, 4,5. But I do not get the Approve button. I see that WF is going to error. May I please know how or Where do I add Approver for this WF.