It's a false positive. They're common with adult visual novels. The anti-virus software can sense the filthy degeneracy within.
Idk. I've played over a hundred AVN's from itch, never once were they flagged as a virus. This one flagged for me as well. 🤷
Where there's smoke, there's usually fire.
And sometimes where there's smoke, there's some twenty-year-old hipster vaping up a storm in front of Walmart. 🤷