Ariba Purchase Requisitions Approval using SAP Workflow Management - Error 401

[RTorres]

Hello experts!

I'm trying to implement the PR approval process using SAP Workflow Management, following this documentation:

However, I am not able to make the CPI access the Workflow Management. I tried to recreate the instances and access keys, register again but the error remains:

401
{
"error": "unauthorized",
"error_description": "Full authentication is required to access this resource."
}

I'm also trying to reproduce this request via Postman, but without success:

Any suggestions to solve this issue?

Note: Tutorial links are in the first comment.

Regards!

[RTorres]

Tutorial:
https://api.sap.com/odata/1.0/catalog.svc/Files('76cc41f3-f02e-4400-8a2a-9af857619470')/$value

https://api.sap.com/odata/1.0/catalog.svc/Files('f94e0cdf-3ce1-4054-90ab-b65f3f27dbd9')/$value