We've already updated our 2 AcyMailing integrations. There's 1 in CB Auto Actions and 1 in CBSubs AcyMailing. If using either be sure to update.
This is solved but new users cannot register on the website. This does not work over the registration form nor over the Facebook Connect.
How can I get it to work?
I've no idea what you mean by this. They can't subscribe to newsletters or they can't register in CB at all? If they can't register in CB then enable debug mode and maximum error reporting in Joomla global configuration and retest to expose any errors occurring.