Can NOT install GA4 Trial

I’m running Windows 8.1

I’ve downloaded the Groove Agent 4 trial, but when I try to install it, at each of the 3 parts, I get an Error Code: 1603.

I’ve seen a few posts about this suggesting that it means I don’t have enough hard drive space, but I have 409 gigs free, so…no.

I also saw something about a particular windows update causing that program, but I don’t have that update installed.

I’m very interested in the software, but I DO at least want to give it a trial run first…but I get nowhere with the installation, and after scouring the various forums, cannot find a solution.