In order to add support for a plugin that uses front-end forms, please add the following code to your theme’s functions.php file.
Alternatively, if you’d like more control over the notifications from your front-end form, please see this support document on how to trigger a notification using an ACF front-end from.

This isn’t always guaranteed to work but it’s a good start. If you need to add support for themes with front-end forms, please see this help document.