• Create the privileged container Debian 10 (template found into Proxmox) but DON'T START IT!
• Modify the configuration of the container into the Proxmox:

  root@proxmox:~# nano /etc/pve/lxc/<CT-id>.conf
  and enter at the end:
  lxc.apparmor.profile: unconfined
  lxc.mount.auto: cgroup:rw
  lxc.mount.auto: proc:rw
  lxc.mount.auto: sys:rw 

• start the container

 apt-get update => apt-get dist-upgrade => reboot 

See https://github.com/OpenMediaVault-Plugin-Developers/installScript/blob/master/README.md
For the container Debian10:

# apt-get install wget sudo
# wget -O - https://github.com/OpenMediaVault-Plugin-Developers/installScript/raw/master/install | sudo bash 

From the browser,

• go to http://the.ip.of.container
• login: “admin” and password: “openmediavault”