iScreensaver 6.9.0 won't install into OS Ventura 13.7.2

I’ve installed iScreensaver 6.9.0 on iMac late 2017 running Ventura. After loading 119 photos (of elephants) to create 'Elephant Magic.isc", clicking the Installer button brings up a passive Install screen where 'Install" button is dimmed and inactive.

When using the ‘Preview’ button, the photos cycle on screen but with warning
“This screensaver is not licensed for distribution. Please visit iScreensaver.com for more information.”

After reading that OS section, I note that 500MB free space is required: internal disk has 244GB free.

Can anyone advise what I am missing, please?

This is the tab within the iScreensaver Designer editor where (1) you edit the installer window. After you (2) build and then (3) run the installer, you will see that screen.

So you’ve done step 1, but not 2 or 3.

iScreensaver Designer can be used in a free demonstration mode, but to build screensavers for use you must purchase a license. See iScreensaver : Secure Store

Sounds like your first use of the software? You may want to read the QuickStart guide which will walk you through step-by-step.

Start here: iScreensaver : User Guide Help