app/views/downloads/show.html.erb
<% content_for :additional_navigation do %>
<div class="content">
<%= button_to 'Download', { action: :file }, method: :get, disabled: ( @download.ready? ? false : true ), class: ['button', 'normal-input', 'button-default'] %>
</div>
<% end %>
<%= render(partial: 'shared/data/project/show', locals: {object: @download}) -%>