Fatal Error

I installed the plugin, entered the API key and then my dashboard crashed and I received the following error:
Fatal error: Class ‘WC_Mailchimp_API’ not found in /home/bransongia/public_html/wp-content/plugins/woocommerce-mailchimp-integration/includes/class-wc-mailchimp-integration.php on line 109

Dashboard stays crashed until I delete the plugin from the server. When I reinstall it, the fatal error happens immediately upon installation. This is for a cleint. pleas help. Thank you