Question about Amazon orders to PR

Hello everyone - I’m planning to order some things and have them shipped directly to PR via Amazon. One thing that is confusing me - the address I’m shipping to has both a postal address (PO box) and a physical address (for FedEx and UPS). I’m unsure as to which address to use since Amazon doesn’t specify which shipping service they use. I was told that USPS has to go to the postal address, while other shippers have to go to the physical address.

Does anyone have any experience with this and have any recommendations about how best to manage this order?

Thank you!