Using the Approvals App in Teams, I built several approval templates.

I would like to build a flow, so that when a Reimbursement Request is Approved (for example), the payroll department receives a message in Teams and a Task is added to their To Do list. (In this case, Payroll doesn't request or approve the item, but must be informed that the item has been approved.)
However, I can not figure out how to use the Approval templates as triggers. Any ideas?