I'm new to Proxmox and I'm looking for where to download, for example an SSH container template, but I can't find any answers, does anyone know where I can find it?
Proxmox can manage LXC containers. These are more than just Docker containers and are similar to leightweight virtual machines.Therefor you do not just have an "SSH container".
Proxmox offers to download many turnkey linux templates when you open a storage and go to "CT templates".