Failed to compute HMAC Authentication for register channel webhooks IN STAGING ENVIRONMENT

I'm working with a NestJS server to handle webhook requests from Deliverect, which include an HMAC signature in a request header.

I'm extracting the raw request body as a buffer using NestJS's body parser and using Node.js's crypto module to compute the HMAC hex digest, with the channelLinkId as the secret key, as specified in Deliverect's documentation.

However, the HMAC I compute consistently fails to match the HMAC provided by Deliverect. Can you provide a detailed explanation of how to correctly verify Deliverect's HMAC signature and ensure the computed value matches the one received?