To achive user->proxy->tor->internet method, I’m a Non-Qubes-Whonix user, that I have to run the proxy software run under the linux user account “tunnel” on Whonix-Gateway. To login, What’s the account password, where to copy the proxy software to, any permission change to the proxy files?
There is no password.
To run commands as that user, open bash under user tunnel.
sudo -u tunnel bash
Or set a password if you want to login for real.