It doesn't show properly in Zorin 18.1, see screenshot.
Hi, Kalarm was built for KDE Plasma.
To work you would need to install kde-standard. Zorin uses the Gnome DE.
Have you ensured that alarms are enabled or start monitoring?
Depending on what you want to do perhaps Gnome Clocks would be better? I think Zorin already has this but can't remember if it is possible to create a tray icon: