Add additional details to staff order notification

I added some custom fields at the cart page, which are added to an order as additional details. I would like to add these to the Staff Order Confirmation and to the Fullfilment service notification. I tried to add several codes, but it doesn’t work. Example:

Uitsparing

    {% for attribute in order.attributes -%}
  • {{ attribute.first }}: {{ attribute.last }}
  • {%- endfor %}

What am I doing wrong? How can I add this?