PayPal Payflow Pro not allowing user to buy product
No one but me seems to have encountered this problem. But in the oft-chance someone ever does encounter it, here's why. 

This error is occurring because I had removed the default address field from the customer profile > billing information in my drupal commerce store in favor of custom fields. But you apparently HAVE to use the default dynamic address field, or at least I don't know a way around it. 

Since most of those fields are valuable anyway, and I just wanted them really in a different order, I found it valuable to KEEP that field, add some custom fields as well, and then just re-order them using hook_form_alter() and the '#weight' property of each form element. Additionally using this function you may also hide any of the fields in the default address field (it contains multiple fields) that you don't want.