Streams followed api returning 401 unauthorised

API
4

You need to use a flow that grants a User Access Token as per the table on Authentication | Twitch Developers

Procedure User Access Token ID Token App Access Token
OIDC Implicit Code Flow :heavy_check_mark: :heavy_check_mark:
OAuth Implicit Code Flow :heavy_check_mark:
OIDC Authorization Code Flow :heavy_check_mark: :heavy_check_mark:
OAuth Authorization Code Flow :heavy_check_mark:
OAuth Client Credentials Flow :heavy_check_mark:

usually:

OAuth Authorization Code Flow