Do I need Zendesk in order to use CXBOX Hub?

Yes, you need to subscribe at least Zendesk Suite Professional in order to use CXBOX Hub. The reason is CXBOX Hub is deployed by plugging with Zendesk via Sunshine Conversations or Conversation API module bundled together with Zendesk Suite Professional Plan.

By fully integrating with Zendesk, you will be able to handle a full-loop customer engagement tasks efficiently.