How to use Collabora? All I get is "OK".

Hi all, I am trying to use Collabora online, but am stuck. I set it up via the docker instructions here (https://sdk.collaboraonline.com/docs/installation/CODE_Docker_image.html).

But when I go to https://127.0.0.1:9980/, all I get is "OK". The reverse proxy works, but the same "OK". How do I actually use the Collabora?

I am anticipating a web interface to a document editor by the browser.