Using your subscriber list from MailChimp, you can easily transfer this list from MailChimp to Cerkl. Through MailChimp you can choose to export an entire list at once or a segment of a list. If you have already created segments through MailChimp, and plan to continue using these same segments, then it is best to export by segment so that you can more easily import these same segments to Cerkl.
For more details on how to export subscribers from MailChimp, you can visit the company's website here.
Once you've exported your subscribers from MailChimp, you can import them into your Cerkl. You can read more about this here.