If you have already downloaded it, open it with an app like Apple Books , Google Play Books , or Calibre . The metadata (Title and Author) should appear immediately.
Look back at the website where you found the link. The page title or the description next to the download button usually lists the book's name. Datei herunterladen xjeg55ytw838.epub
On a computer, you can sometimes right-click the file and check "Properties" or "Get Info" to see if any tags are embedded. If you have already downloaded it, open it