It might have been represented as a document "to 'use as interactive', like a 'form to fill in'", but that isn't what it is.
It's no wonder you're having trouble - it's a dog's breakfast because of the way it's been produced.
See if you can get hold of the original PDF. If well-designed it may have PDF fields you can fill in. Otherwise, try opening the PDF in Word, which may do a better job of the conversion than whatever was used to produce the document you've been given.
Of course, it's even possible the PDF was itself produced using Word, in which case it would be nice if those who want you to fill in the so-called fields supplied the original Word document...
PS: Judging by the letterhead, the document originated at:
AICSA | Peak body in South Australia | Conveyancing Profession