There's a newer version of this sample taking advantage of the Microsoft identity platform (formerly Azure AD v2.0) and MSAL.NET.
Check it out: https://github.com/azure-samples/active-directory-dotnetcore-daemon-v2.
If you really need to access this Azure AD v1.0 | ADAL.NET sample, you can navigate to the master branch, but please know that it's no longer supported.