Thanks very much for your reply, Jeremy. I have now installed ente-auth on my Debian Bullseye desktop PC.
I downloaded ente-auth-v2.0.50-x86_64.deb from GitHub. I then installed it using apt install. I found ente_auth@ in both /bin and /usr/bin I thought I needed to run this in order to launch ente-auth, so typed ente_auth@ but my system said the command could not be found. Any suggestion as to what I am doing wrong, please ?