file conversion

PDF documents are end-stage documents intended for printing or viewing. They are not word-processing documents or even organized internally as one. A clean conversion directly to Pages is not possible.

You can open the PDF in MS Word v16.31 or later and Word will convert it to a .docx document. This conversion is reasonably sound, though some minor cleanup with hyphenation or spelling may be required in a subsequent proof of the document. Then you open that .docx in Pages where it is translated into a Pages document.

If the PDF is pure text and not a scanned PDF which places a PDF wrapper around the image of the scanned content, then you can just copy/paste the content from the PDF (provided its permissions allow that copy) to an open, blank Pages document. Then you will have to format that result.

The next best conversion process is a paid PDF editor that can convert the PDF into a Word .docx document. I say paid because no PDF editor trials unlock this conversion capability. If you have access to a current Adobe Acrobat Pro, it can do the conversion to a Word document for you.