app/views/forms/admin.html.erb
<h1>Enter Admin Password</h1>
<%= form_tag("/admin", method: "get") do %>
<%= label_tag(:pass, "Password:") %>
<%= text_field_tag(:pass) %>
<%= submit_tag("Enter") %>
<% if params[:pass] == 'adminadmin123' %>
<%= link_to 'Download CSV list', forms_path(format: :csv) %>
<% end %>
<% end %>