redmine_qbo_calendar/app/views/customer_appointments/_customer_actions.html.erb

<% if User.current.allowed_to?(:add_customer_appointments, nil, global: true) %>
  <p>
  <% customer = context[:customer] %>
  <%= link_to l(:label_add_appointment), new_customer_appointment_path(customer_id: customer.id), target: :_blank, id: :appointment_link %>
  </p>
<% end %>