A PDF of the Quran is still a Mushaf. You must treat it with the same respect as a physical book. Do not take it into the bathroom, place it on a dirty floor, or delete it disrespectfully.
While downloading is free, ensure the PDF does not contain ads, malware, or altered text. Always verify the scan with a physical copy of the Taj Company Quran. quran-e-pak taj company 16 lines pdf free download