There's a newer version of this sample taking advantage of the Microsoft identity platform (formerly Azure AD v2.0)
Check it out: https://github.com/Azure-Samples/active-directory-javascript-singlepageapp-dotnet-webapi-v2
If you really need to access this Azure AD v1.0, you can navigate to the master branch, but please know that it's no longer supported.