If the Pupil ID is already set to UPN or Admission number and you have previously imported pupil data (you can check this by clicking on the Accounts tab), refer to How to switch Pupil IDs in Schools Cash Office

If the Staff ID is not set to StaffID and you have previously imported staff data (you can check this by clicking on the Accounts tab, View staff), refer to Add Staff.  Update the staff IDs prior to setting up the MIS Link.