Amazon doesn't accept PayPal, likely because it is a direct competitor to Amazon Pay. The way around it is to buy Amazon Gift cards from other sellers.

PayPal Cash Card or Amazon gift cards purchased via PayPal are two of the best ways to harness your PayPal balance for Amazon orders. If you prefer credit rewards, you can add a PayPal-linked ...

Amazon has expanded Buy with Prime, its fulfillment service for third-party e-commerce merchants, with a new PayPal payment option.