The most common way to send an email to someone internal for each new subscription is to use Zapier. There is a help guide on how to do that here: https://help.convertkit.com/en/articles/2502647-how-to-get-email-notifications-for-new-subscribers-purchases-and-unsubscribes34

Blair Wadman🌟Community Influencer 🌟
Email Automation Consultant - blairwadman.com