Only paid plans may bind custom subdomains.
Failed to bind the custom subdomain
SUBDOMAIN for an unauthenticated client.
Sign up at: https://dashboard.ngrok.com/signup
If you have already signed up, make sure your authtoken is installed. Your authtoken is available on your dashboard: https://dashboard.ngrok.com/get-started/your-authtoken
If you're having trouble resolving this error, please reach out to firstname.lastname@example.org