Can't Connect to Mailchimp API

Hello,

I’m trying to set this plugin up for a client, but the MailChimp API doesn’t seem to want to connect. I receive the following errors:

Warning: sprintf(): Too few arguments in /home/yonfpmyc/public_html/wp-content/plugins/woocommerce-mailchimp/classes/class-ss-wc-integration-mailchimp.php on line 379

Unable to load lists from MailChimp: (-99) Could not connect (ERR : ).

ETA: This is currently what is on line 379, if that helps:
sprintf( __( ‘Please check your %s settings.’, ‘ss_wc_mailchimp’ ), WOOCOMMERCE_MAILCHIMP_SETTINGS_URL )

I should mention that she has other plugins which are able to connect to the MailChimp API just fine. Any idea what could be going wrong?

Thank you!

https://wordpress.org/plugins/woocommerce-mailchimp/