I have done the steps you mentioned and created hub-external.yaml and hub-templates.yaml files to my jupyterhub helm chart template folder…
also helm upgrade with
jupyter hub pod renders html files in mounted volumes but when doing login page.html line 125 which wants to inject admin:user and cannot render the page due to error…
before these configuration I could not see the admin pannel either…
this is Error from running kubectl logs -f 
{% if ‘admin:users’ in parsed_scopes and ‘admin:servers’ in parsed_scopes %}
jinja2.exceptions.UndefinedError: ‘parsed_scopes’ is undefined
How can I customize branding and logo and html files with this way or other method like extra cofigFile?
tnx;