CCBChimp is an approved 3rd party app to sync CCB to MailChimp.
So, if you have CCB/Mail Chimp, you will have to pay to add CCBChimp.
Getting just a CCBChimp account does not include the cost of MailChimp—adding MailChimp will be an additional cost.
Please realize though that the MailChimp free tier is impressive and offers 2000 subscribers and 12k emails per month. If that isn’t enough, they offer 15% discount for non-profits.
You can use this calculator to estimate cost.