I assume you have Adobe standard. You would need Adobe professional to be
able to have the pdf conversion result in a fill-in form. It's an expensive
"fix" - if you don't want to go that route, as an alternative you can post
your Word form (which should be locked so only the form fields can be
changed) for users that have Word and also post the non-interactive pdf for
users without Word to download, print and fill in manually.