AE Plugin : Unauthorized error (401) in Advance Rest Client plugin for "http" API

I am getting unauthorized error (401) in Advance Rest Client plugin for “http” API.

The HTTP 401 Unauthorized client error status response code indicates that the request was not applied because it does not have valid authentication credentials for the target resource. This status is sent with a WWW-Authenticate header that contains information on how to properly authorize.1

IT seems that the issue is regarding your API credentials or authorization methods, not the STEP itself.