If you are a programmer you need Microsoft Visual Studio Enterprise which is $5,999/user/first year and includes Team Foundation Server online access & Microsoft Test Manager stand alone app.
Anyone doing just QA and no programming can use Visual Studio Test Professional which will cost your company less $2,169/user/first year and only includes Team Foundation Server online access & Microsoft Test Manager stand alone app.
With Visual Studio Team Services all the functionality of Microsoft Test Manager is built into the cloud and accessible via web-browser so there is no need for the stand-alone windows application. The only additional functionality of the stand-alone windows application is the ability to record video of test case steps. You can add test cases in the web browser under Project > Test > Test Plans.
Here is the Visual Studio Product Pricing Breakdown from Microsoft:
Here is an example of Test Manager in TFS:
Here is an example of Microsoft Test Manager stand alone windows app with similar functionality:
If you have any further questions you can always contact MSDN team at 800-759-5474 M-F 5:30 AM-5:30 PM PST as well for your technical questions or you can chat with a sales technician through their website @ https://www.visualstudio.com/vs/pricing/#tab-d83539eb2b4c2400472