You can sync prompt response to create/update Mailchimp subscriber.
Connect to Mailchimp
Go to prompt connections page and connect to your Mailchimp account. Mailchimp subscriber sync option will only be shown to accounts that are connected to Mailchimp.
Mailchimp Subscriber Sync
Edit prompt and select
Sync. Then locate
Mailchimp Subscriber and turn it on.
All other configurations and fields are optional.