Visual Studio Team Services Package Management API

So, much research has shown that the only way to push a NuGet package to the VSTS Package Management is with the CLI tools vs the NuGet Package Explorer app. So, I'm hoping to fix that to make life easier.

Initial research makes me think that I can use one of the REST APIs that Microsoft offers. When I use the link below in Postman, I get the response back that would normally be the Microsoft login page, which is what I would expect when I'm not passing any authentication in the GET request.

https://fabrikam.feeds.visualstudio.com/DefaultCollection/_apis/packaging/feeds/EngineeringInternal/packages?api-version=2.0-preview

However, when I replace the demo account and feed name with my own, I get a 401 error.

https://sartainsoftwaresolutions.feeds.visualstudio.com/DefaultCollection/_apis/packaging/feeds/SartainSoftware.Common/packages?api-version=2.0-preview

Unless I have to enable access to the given API in my VSTS account, I'm not sure what I'm missing.

Any thoughts?