PDF to Word rebuilds selectable text into a .docx file in this browser. It is for editing paragraphs, not for cloning a designed layout.
A scanned page with no text layer will not become editable words. Columns, headers, and tight tables often need a cleanup pass in Word.
Questions
Is the Word file a perfect copy of the PDF?
No. Text is rebuilt locally. Complex layouts and scanned pages need editing after you download the .docx.
Do you store the document?
No. There is no account and no file is kept after you download.