That it's not actually a virus, computer just freaks out for nothing.
Generally people aren't going to make a video game just to spread a virus. You're safe to download pretty much any visual novel with a bunch of comments and ratings on itch.io
Also here's a piss easy way to test if you have legit 0 PC knowledge. Install the VN on your phone. Phones can't get viruses. You can then play and see it's a real vn