I think he means the setting that switches from a light theme (ZorinOrange-Light) to a dark theme (ZorinOrange-Dark) based on time of day. Right now it wouldn't really make sense to have it working for user added themes because there is only an option to select one theme. There would need to be a place to select 2 user added themes, one for day and one for night. I think it's very probable there are some apps out there that can cycle a theme based on time of day?
I hadn't performed any customizations or made any system-wide changes, just installed some everyday utilities. but if it helps I have no problem testing it.
It's simply because Zorin Appearance is hard-coded to behave this way. There is a matching light/dark theme for each accent color that gets selected when you use any of the available options. Anything beyond this needs to be applied either through Gnome Tweaks or through the command line:
For example, here's one case where the user wanted a dark taskbar but retaining the light theme on other windows, and my work around for it:
And a similar issue with resetting the icons:
EDIT: Looking at this thread now, you might be able to get away with setting your own profile right there: