Problem: I can't have an Access Token

Hello, I have a problem, with your explication on your API : "https://powerbi.microsoft.com/fr-fr/documentation/powerbi-developer-walkthrough-push-data-get-token/"

I can't have an Access Token, because I have meet two problems with you explication.

1. I can't install the package "Microsoft.IdentityModel.Clients.ActiveDirectory" with the version "2.21.301221612", because when I try to install this package, the console tell me:  some of the package s that will be installed are incompatible with " .NetCoreApp, version = v1.1". But I can install the last version 3.13.9. I have search on your API, the Forums, and the Internet an explication but I haven't found any informations. I would like some explication and perhaps a solution.
2. When I retrieve the Code on your page for "Visual Studio" , a can't use the methode:  " String token = authContext.AcquireToken(ressourceUri, ClientID, newUri(redirectUri)).AccessToken;  "
   I suppose this is a problem with the version of the package I have install, but when I go on the API in order to found an other solution, I realise the documentation haven't the last version on the methods. The API are with the version 2.19.208020213. And I found the information are not very details. I don't found the help I search.

I'm waiting for you answer, 

Sarah Q.