If you don't see the CIS system accounts in ApprovalMax, it indicates that the Organisation is not CIS-enabled. To use CIS transactions, the Organisation needs to have CIS enabled in Xero.
Contacts cannot be enabled for CIS through ApprovalMax. This step must be completed in Xero prior to using a Contact for CIS transactions. Once a Contact has been enabled for CIS in Xero, the Contact becomes eligible for CIS-related activities.