You can review students with past-due payments to prioritize follow-up.
Who: School Admins / Finance Managers · Where: Insights › Reports (delinquent/past-due), and each student's contact record
For a school-wide view of overdue balances, go to Insights › Reports and open the student payment / delinquent-payment report (see "How can I access and manage student payment and delinquent payment reports in Lumion?"). For a single student, open their contact record and check the Payments tab and Outstanding Balance.