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 ?