Check the "Create Bookmarks Using:" option under the "Include non-printing information" header. Choose whether you want Word to create bookmarks from the document's headings or Word bookmarks.

The PDF equivalent of the navigation pane is the bookmark pane, which holds links that act as interactive index tabs. Several resources make creating this pane's links easy.

Select Export bookmarks and click the Export button to create a PDF form. Once done, you can open the file in a PDF viewer. To test the functionality, you can fill up al the blank fields and save.