In ApprovalMax, Purchase Order numbers are not generated by ApprovalMax but assigned by your connected accounting system once a Purchase Order has been fully approved and sent through.
Purchase Order numbers are assigned automatically by QuickBooks Online when the Purchase Order is fully approved in ApprovalMax and sent to QuickBooks Online.
By default, QuickBooks Online assigns Purchase Order numbers automatically in ascending order (e.g. 1001, 1002, 1003) - unless the option Custom Transaction Numbers is enabled in your QuickBooks Online settings:
If Custom Transaction Numbers is turned OFF: QuickBooks Online will automatically assign a number to the Purchase Order when it's received from ApprovalMax.
If Custom Transaction Numbers is turned ON: QuickBooks Online expects the Purchase Order number to be entered manually. In this case, ApprovalMax does not receive or assign a number, and the Purchase Order number field will remain blank in ApprovalMax.