For a user to be able to manage FiboSearch settings, they have to be assigned the manage_options value.
By default, only site admins were able to manage FiboSearch. It is also possible for users assigned the “Shop Manager” role.
You can establish this by adding a constant to your wp-config.php :
define( 'DGWT_WCAS_ALLOW_SHOP_MANAGER_ACCESS', true );