Env Variables need to be created:
MAILCHIMP_API_KEY. MAILCHIMP_API_SERVER. MAILCHIMP_AUDIENCE_ID.
https://cesko-digital.atlassian.net/browse/ZU-445?atlOrigin=eyJpIjoiNzhkNzVhYmVjYTU3NGQ1ZWI2NGIxMjE4ZGQ2OWRlNzAiLCJwIjoiaiJ9
https://cesko-digital.atlassian.net/browse/ZU-444?atlOrigin=eyJpIjoiYWNiYjYwMTllNzFjNGNmYjgyYWI3YzE2ODNmOTBmNTgiLCJwIjoiaiJ9