I'm having similar issues connecting my Conbee II into the HA integrations, I'm still getting the error - "Couldn't get an API key", this is after pressing authenticate app button within the Phoscon app. Deconz recognizes my host address but that's about as far as I can get. I suspect it's something to do with how my containers are configured on the network. I have tried changing the networks within each container, HA or Deconz but with some options I cannot access the webui to complete the integration. Hope this makes sense.
Any help would be greatly appreciated 👍