This plugin does not sync with Mailchimp Webhook.

Sorry to hear that you had trouble with the plugin. It was tested quite thoroughly with MailChimp and I can assure you that it does work as intended. Could you specify what didn’t work for you? Did the discount code not get generated? Did the email with the discount not get sent to the customer?
Also, please check that you followed all of the setup steps found here. If it still does not work for you after following those steps, please open a support ticket with the details of what you’ve tried and what went wrong and I’d be happy to help resolve the issue for you.