Please do not send us purchase orders because we do not process them.
You already have everything you need to make the payment, including an invoice (see I need an invoice (for the Article Processing Fee, submission fee, etc...)) and our bank information (see Can I pay by wire/bank transfer? Where is your bank account information?) and a link for credit card payments. Please communicate this information to your finance department and make sure the invoice is paid. You may have to complete an internal purchasing requisition or purchasing order, but this is between you and your university administration and we cannot assist with your internal processes.
We can only continue with processing the paper once we received the funds. We are not accepting a PO in lieu of payment (much as you wouldn't be able to book a flight without paying for it).