Please update the Verge and Amazfit APP to the latest version.
After updating the firmware and app, please go to the Workout page in Amazfit App➡ sync manually by pulling down in the home page and click Profile➡Add accounts➡Amazon➡click Login with Amazon➡Sign in➡fill in Amazon account and password to activate Alexa account.(Alexa function on Verge is available in US for the current stage.)
Please refer to the video from the link below:
https://drive.google.com/open?id=1xhIPTVjMOiw05k8q5wKB8IPvHJuG7_dk for your reference.