I currently try my first steps in Sitefinity development to have a permission set roled out on several Sitefinity instances.

Therefore I wanted to work with the Security library of Sitefinity and follow the Permissions and Roles documentation.

However, I do not have any intellisense to any of the Sitefinity classes. That makes me doubt if the project is working properly with Visual Studio 2019.

I tried to install the Nuget packages as described in several documentations (see below). However packages, such as Telerik.Sitefinity.All or Progress.Sitefinity do not exist in the global Nuget repository. 

How do I get these? And why does intellisense not work as intended?

The documentations I used:

https://www.progress.com/documentation/sitefinity-cms/create-widgets-in-external-assemblies-mvc

https://www.progress.com/documentation/sitefinity-cms/install-sitefinity

https://www.progress.com/documentation/sitefinity-cms/for-developers-grant-and-deny-permissions

https://www.progress.com/documentation/sitefinity-cms/for-developers-roles

The following snippet does not throw any recomendations: