Do I need to set up both webhooks to use the integration?

No, you don't. If your company uses the “Create Offer” button in Greenhouse to finalize your new hires, then you will set up the Offer Created webhook. If your company uses the “Mark Candidate as Hired” button in Greenhouse to finalize your new hires, then you will select the Candidate Hired webhook.

Note: Only the Offer Created webhook requires OAuth credentials in Remote. The Candidate Hired webhook does not.