Do you use the free version of the plugin? Support for the free version of the Cerber Security plugin is provided on a support forum: https://wordpress.org/support/plugin/wp-cerber/
If you use the Professional version of WP Cerber Security, please submit your support request via our helpdesk: https://my.wpcerber.com/
Note that before submitting this form you must submit a support request on the support forum or get an invitation from our staff. All blind form submissions are ignored.