Set up collabora server via docker-compose for use with Hetzner hosted Nextcloud instance

I have a Nextcloud instance via Hetzner. I would like to use Collabora CODE to edit online documents with my own server to handle Collabora docs.

I have a vps with docker running and have run the following image via docker-compose:

version: "3.5"
    image: collabora/code
    container_name: collabora
    restart: unless-stopped
      - extra_params=o:ssl.enable=false
      - domain=nx123456\\.your-storageshare\\.de # the domain of my nextcloud instance (amended to be fictional)
      - dictionaries=en_US
      - "9980:9980"
      - ./appdata/collabora:/config

After running this container, if I type curl -k https://localhost:9980 in the terminal I get the OK string. So all seems well?

Now I have two separate cloud entities. My Nextcloud instance and my VPS running Collabora code via docker-compose.

Both of these services are separate and independent of each other, yet they are both provided by Hetzner.

If the domain of my Nextcloud instance is e.g. nx123456\\.your-storageshare\\.de and if the IP address of my vps is e.g. (fictional) 123.456.789.123, what should I do next to connect these services so that I can use my collabora server with my Nextcloud instance?