unauthorized access to reports in a group

I'm trying to access the reports shared in a content package under a group I'm a member of through the API. It seems pretty simple in this link https://msdn.microsoft.com/en-us/library/mt634543.aspx, however, I get "The remote server returned an error: (401) Unauthorized.". I'm able to get reports in my workspace and also the group_Id through the same api and same credentials. I have given permissions to my app to all view groups, view user groups and view content properties, which I'm not even sure if I need. Am I missing or misunderstanding something?