error in paid version / no settings

Our client purchased the plugin. an error is showing and settings are not accessible.
Please advise with solution.
We’d be happy to share the error report via a private form.

CLEANTALK_AJAX_USE_BUFFER NOT_DEFINED
CLEANTALK_AJAX_USE_FOOTER_HEADER NOT_DEFINED
CLEANTALK_ACCESS_KEY NOT_DEFINED
CLEANTALK_CHECK_COMMENTS_NUMBER NOT_DEFINED
CLEANTALK_CHECK_MESSAGES_NUMBER NOT_DEFINED
CLEANTALK_PLUGIN_DIR WP_ALLOW_MULTISITE NOT_DEFINED`

The page I need help with: [log in to see the link]