Where is the documentation for the creation of Tenant templates that include MSTeams?

[web265p3]

I know that its also possible to create Tenant templates with the PnP Powershell:
Tenant Templates

I expected the code in this repository to work almost equal to the Pnp.Sites.Core, but the following code throws an exception:

        using (var context = pnpProvisioningContext.GetContext("https://ourOrg.sharepoint.com/sites/siteSegment"))
        {
            var tenant = new Microsoft.Online.SharePoint.TenantAdministration.Tenant(context);
            var ec = ExtractConfiguration.FromString(System.IO.File.ReadAllText("C:\\temp\\teamExtractConfig.json"));
            var template1 = tenant.GetTenantTemplate(ec);
            XMLTemplateProvider provider = new XMLFileSystemTemplateProvider(@"C:\temp\teams.json", "");
            provider.SaveAs(template1, "TeamTemplate.xml");
          }

The following line causes the problem in this repo:

var accessToken = PnPProvisioningContext.Current.AcquireTokenWithMultipleScopes(graphBaseUri.Authority, "Group.ReadWrite.All", "User.Read.All");

Its located in the function "ExtractObjects" in the File ObjectTeam.cs.

PnPProvisioningContext.Current is null here...

The exception seems to be related to authentication, but I am sure my authentication is configured fine, because I can extract normal site templates without problems: