Assuming you avoid the viruses, the "PDF" you find is likely a poorly scanned, OCR-generated mess. Pages will be crooked, text will be blurry, and the file will likely cut off the final chapter. Is a headache-inducing scan worth ruining the literary nuance of Moshfegh’s prose?
You can often read the book for free or at a low cost through legitimate channels: Public Libraries Lapvona Free Pdf