Docker is a popular tool for running application containers. It's supported by vpsAdminOS with two caveats. First, containers that you want to run Docker in have to use a different seccomp profile:
osctl ct set seccomp <id> /etc/lxc/config/common.seccomp
The default seccomp profile denies access to kernel keyring, but Docker (more precicely runc used by Docker) needs access to the keyring by default.
The other caveat is that only VFS storage driver is available. That's because the default overlay driver does not work on top of ZFS.
The latest Docker version can be installed by following the manual for your distribution, e.g. https://docs.docker.com/install/linux/docker-ce/ubuntu/.