Hi,
Could you check out this related topic, please? https://www.pixelwars.org/forums/topic/newsletter-not-working/
1-) for popups I just navigated to JetPopups > Settings, clicked sync and saved and attached a popup to the button on your hero section and I can subscribe to your list with success.
2-) for on-page subscribe forms such as the subscribe section on your footer I navigated to Elementor > JetElements Settings > Mailing List Manager then put your mailchimp api key and list id then saved, and it works fine now, too.
Btw, here are some tutorials on this topic;