Hi there,
Jennifer is on the right track! If your buyer selected PP as their preferred payment method, in addition to the EW invoice you will need to send your buyer a direct PP invoice. You can find instructions here:
https://www.etsy.com/help/article/367Once payment is received you will be able to mark your PO as paid.
If you would like your buyers to be able to submit payment directly on platform, you can disable PP from your Wholesale policies so that they only payment method is Direct Checkout which will allow your buyers to submit payment immediately.
Hope this helps! If you need further assistance, feel free to get in touch with us directly at wholesalesupport@etsy.com