Can't install new theme

Just purchased the latest Directory Opus (upgrade) and I'm experiencing cognitive dissonance. I followed the instructions in the online manual but I don't see any Load or Import option to install my theme. And my current theme isn't listed either.

One more question: why isn't there any new themes for Directory Opus. No one is supporting it. Why?

Use File > Import Theme to load a new theme file into the list.

You can also click the help "(?)" button, top-right, for more details on how to use the dialog.

Okay, but where are the themes? I can't find anything as a dlt file?

2nd post (at time of writing) in the themes area has one (once you unzip the download): PSU.

Several others are there.

Some posts contain config backups as well as, or instead of themes, which I would not recommend. But many of them contain .dlt themes if you look.

Hmm. Okay, thanks.