How to turn this into a PDF? Most official platforms have a "Print" limit, but you can use the "Share" or "Export" feature in some reading apps to create a personal backup—though this is usually against the Terms of Service.
For leak prevention, use dynamic per-recipient visible bloodmarks combined with invisible forensic watermarking, test across platforms, limit personal data exposure, and document legal/compliance obligations. bloodmarked pdf
Even if you find a PDF, it is likely a scanned copy of the physical book. This means: How to turn this into a PDF