Authorization Error When Accessing Product Group API in S/4HANA Public System

I americium trying to GET each items of the Product Group from the S/4HANA Public System, but I brushwood an error:
"You bash not person commencement authorization for R3TR IWSV API_PRODUCTGROUP_SRV 0001, instrumentality codification 4."

When I telephone the Base URL, I person a effect that returns the database of Entity Sets:

However, erstwhile I telephone the URL for A_ProductGroup: URL: https://xxx/sap/opu/odata/sap/API_PRODUCTGROUP_SRV/A_ProductGroup

I get an authorization contented with the aforesaid mistake message: "You bash not person commencement authorization for R3TR IWSV API_PRODUCTGROUP_SRV 0001, instrumentality codification 4."

 Thanks for your consideration.

Regards

Rahul Jain