Since PeopleCert acquired AXELOS, the official store is the only place to buy genuine digital PDFs. You can purchase:
Since you cannot get an "ITIL v5 PDF," here is a modern, certified study plan for ITIL 4:
Download the official ITIL 4 Foundation syllabus from PeopleCert. This 15-page PDF tells you exactly what will be on the 40-question exam. No guessing.