v2.1 does not work

The plugin is throwing errors when trying to use it. I can’t save users or edit the settings for the Plugin.

[Thu Jul 20 15:09:38.645650 2017] [:error] [pid 3289] [client 90.254.172.211:30884] FastCGI: server “/var/www/clients/client21/web37/cgi-bin/php5-fcgi-*-80-alive-fitness.co.uk” stderr: PHP message: PHP Fatal error: Call to a member function get_error_message() on a non-object in /var/www/clients/client21/web37/web/wp-content/plugins/pmpro-mailchimp/includes/class.mailchimp.api.php on line 122, referer: http://alive-fitness.co.uk/wp-admin/plugins.php

Please advise.

Thanks, Nick