Azure AD Graph API demo example won't work: The identity of the calling application could not be established
<p>I'm trying to get this demo to work:</p>

<p><a href="https://github.com/Azure-Samples/active-directory-dotnet-graphapi-console" rel="nofollow noreferrer">active-directory-dotnet-graphapi-console</a></p>

<p>But having no success. The steps are very detailed, and I followed them exactly. The userpart of the demo works, that's fine. But the app part won't work.
I'm getting the error:</p>

<blockquote>
  <p>The identity of the calling application could not be established.
  {"odata.error":{"code":"Authorization_IdentityNotFound"}}</p>
</blockquote>

<p>Googled for this, but givens me very few hits. Some with the same problem, but no solutions.</p>

<p>I'm pretty sure my clientId and key are correct, because when I change them I get another error clearly stating the problem..</p>