I solved it in my theme function like this:
// set editor role for contact-form-cfdb-7 plugin
include_once( ABSPATH . 'wp-admin/includes/plugin.php' );
if ( is_plugin_active( 'contact-form-cfdb7/contact-form-cfdb-7.php' ) ) {
// Add custom capability
$role = get_role( 'editor' );
if(!$role->has_cap('cfdb7_access')){
$role->add_cap( 'cfdb7_access' );
}
}
It works, but I am not sure if that is a good solution.