A family of Microsoft word processing software products for creating web, email, and print documents.
I would advise against creating a fillable form in Word for use by people who don't have Word. A better plan is to create a form as a PDF file, because almost everyone has a PDF reader or can download one.
There are many free or paid programs, both installable in Windows or used online, to create fillable forms in PDF format. Read https://pdf.iskysoft.com/pdf-form/free-pdf-form-creator.html or use a search engine to look for "create pdf forms freeware" and read some reviews.