I tested SteamCMD on Ubuntu 16.04 LTS 64-bit
and I was able to log in to my steam account, but I don't have any games on my account
and I can't check is it possible to download commercial games.
Downloading freeware stuff is possible.
I installed multilib
sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install libc6:i386 libncurses5:i386 libstdc++6:i386
and then
sudo adduser steam
then I set password
login
steam
typed password
wget http://steamcdn-a.akamaihd.net/client/installer/steamcmd_linux.tar.gz
tar xjf steamcmd_linux.tar.gz
cd linux32
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/steam/linux32
./steamcmd
login aaaa bbbb xdoko
@sSteamCmdForcePlatformType windows
app_update 740 validate