Fill PDF: forms with fields or scanned pages
To fill a PDF, type into the fields the form already has or, if it is scanned and has no fields, write and tick X over the page. Both go into the same file, which comes out editable or flattened. The PDF opens in this tab and is not sent to a server.
The PDF and what you type stay on your device
PDF and the page to fill
Everything happens in this tab; your PDF does not change, a new file comes out.
Fields on page 1
Missing: the PDF.