Yes—ChannelReply has no independent user interface. You must connect it to Zendesk, Freshdesk, Help Scout, Gorgias, Re:amaze, Zoho Desk, Kustomer, or Onsite Support to answer your messages.
Note: If you do not want to pay for two separate platforms, you can use Onsite Support. ChannelReply is included with every Onsite subscription.