Owned by the Japanese publisher themselves. While they focus on current series, they often rotate classic chapters of Dragon Ball into their library for free reading.
Websites asking you to "complete a survey" or download an ".exe" file. Real manga PDFs are files, not programs. Dragon Ball Z Manga Free Download Pdf
If you want a PDF-like experience, Amazon’s Kindle app allows you to buy digital volumes ($6-$8 each) or rent them via Kindle Unlimited subscription. Owned by the Japanese publisher themselves