Hi,
I’m not a Proxmox expert and have only been testing it out in a VirtualBox installation on my Mac but, having said that, I did manage to get an Alta Control container up and running.
As far as I’m aware Proxmox can’t easily use the LXD container linked in the Alta Control PDF installation guide. I used the “raw root filesystem” tar.gz file linked under “Notes” on the Docker instruction page here.
I selected my local storage in Proxmox, created a CT Template using the .tar.gz linked above and then was able to create a container using the newly created template. That got me a working container.
I can’t guarantee how well it works beyond that as I’m just testing out Proxmox at the moment.
Hope that helps?