AirPods Pro AppleCare+

I bought AirPods Pro from Amazon (via Apple) and I was reassured time and time again that there is no problem adding AppleCare+ on the AirPods if bought from Amazon, yet I go through the link and enter my serial number and I only get this response: "it looks like your device isn’t eligible for an AppleCare agreement."

I don't know what to do. Please Help! thanks