Hello Florian

Thank you for your purchase.

Please download the beta version of Amelia attached to my response.

When you install it, you need to go to wp_options table in the database, and search for "amelia_settings" in "option_name" column. You'll see some new settings for payments.stripe :

"description":{"enabled":false,"appointment":"","event":""},"metaData":{"enabled":false,"appointment":null,"event":null}

By default, that data is not being sent, so they are not set. To send them, you need to change the "enabled" parameter to "true", and to enter the placeholders in "appointment" and "event" parameters, like you'd enter them in an e-mail notification template. For example:

"description":{"enabled":true,"appointment":"%customer_full_name% has booked %service_name% at %appointment_date_time%","event":"%customer_full_name% has booked %event_name% at %event_start_date_time%"},"metaData":{"enabled":true,"appointment":{"user":"%customer_full_name%","email":"%customer_email%","phone":"%customer_phone%"},"event":{"user":"%customer_full_name%","email":"%customer_email%","phone":"%customer_phone%"}}

I hope that helps.