You can only contact the Buyer via ZeusX's in-app chat system, which can be found and triggered from your Notification - Sales tab at the top right corner of the screen

If a buyer messages you, you will see a red notification on the chat icon

An email will also be sent to the email that you signed up with to notify you of any messages from potential buyers

Please refrain from taking conversations outside of ZeusX, this is to protect both buyers and sellers in case of a dispute.