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. With the introduction v1.23 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 );