pgAdmin 4 in an unprivileged lxc container - Mailing list pgadmin-support

I am trying to install pgAdmin 4 2.1 in a Debian 9 container running on a Proxmox 4 host and the install fails saying :
  Could not find a version that satisfies the requirement flask (from versions: )
No matching distribution found for flask

I have already done a similar install but the container was not marked 'unprivileged'.  This time, I marked the container as 'unprivileged' when I created it.

As a consequence, I cannot run the installer as 'root' as it is mapped to an unprivileged user on the host.  All I can do is 'sudo' the commands.

By the way, does pgAdmin 4 require to be installed and run as root ?

Thanks.

Marc