theming – How to add a class to a file link in Twig

I'm trying to add a class of buttons to a Internal file URL. The field itself is a type of normal file field. You will find below the twig code that I tried to use without success. I'm also using this code in a twig field pattern.

{% for the article in the articles%}
 {{Item.content['#title']}}
{% endfor%}