Navigate to Billing/Revenue >> Pending.
From here click 'Download Pending and Upcoming Payments':
You can now decide if you'd like to export both upcoming payments and Pending payments together, or you can export these individually.
Click download CSV and the export will run.
Tip. Want to email a customer/s to remind them they have pending offline payments?
From the pending payments report, filter all offline payment methods (column F).
Filter your desired payment date range (column E).
Extract email/s addresses (column C).
Send email to customer/s from your own mail address.