If the staff member has a current contract with the University (even if they are on leave) they themselves need to grant you access or written approval from the Vice Chancellor needs to be sent to the IT Help Desk approving this access.
NOTE: Obtaining the staff member's login details to avoid the above procedure is in breach of IT Policies. If the IT Help Desk become aware of this the staff member's account will be disabled for security purposes and the IT security team will be advised of the incident.