Clean install with Calamares fails with "Encrypt Disk" enabled. Tried with latest ISO.
Open a bug report in its github page : https://github.com/artix-linux/calamares/issues
Try calamares in debug mode
sudo -E calamares -d
Mine fails too, I will get some more info on the bug page.
The first place I ever saw calamares was siduction (a Debian sid distro). Maybe if you look through their forum you may find some trick to make it work. I think AntiX was also using calamares and they had problems with installing with Luks, I have no idea whether they have come up with a script to make it work since then, unless antix was having problems with luks without calamares :)
Antix/MX was founded in running debian without systemd, so they are good people ;)