The "compose email" button opens up an email draft in your email app (e.g. Outlook, GMail, or Apple Mail).

If doesn't work, it's usually because you have a pop-up blocker or no email app on your device.
​
Don't worry! You can easily copy-paste the email template and email it to your vet yourself. You can even ask your vet in person to claim for you at www.napo.pet/vet-portal. 🤗
​