What is the function of the "is this role an admin role" security role setting?
A user that has been linked to a security role that has been defined as an admin role and who is the final approver in a workflow path, can approve and commit workflow items between the payroll cut-off date and the pay date to the current open run.
Enabling this security role setting will also allow the user to download payslips of an open run.
Navigate > Configuration > Security > Security > Security Roles