Zoho Mail Desktop Lite Client - unable to find Linux .deb version

Zoho Mail Desktop Lite Client - unable to find Linux .deb version

HI, I use this on Linux and went to upgrade my 1.0.3 install to the latest. The download has a .AppImage "file type" not .deb and I can neither install it or run it (it sort of loaded once, made some reference to being concerned if I was running on a share PC and exited).

Where can I download the .deb please?

Thanks

Alan