Hello,
Well, I had the same problem with my students...The only way I found is the Following one :
1/ Open your Word doc with Open Office ( which is free to download ) ( this is very quick ;-)))
2/ Once your document is Open Office ( the usual way : save as..) , then you will be able to create a fillable PDF.
As I am not an expert - !!! far from it -esp in English ;-))) I think it will be easier for you to find a tutorial : create a fillable PDF from Open Office.
I searched the Web, and it seems you cannot do it directly from Word...
Hope I am clear enough :-D
I tried it this week , and it�s perfect ! With the quarantine, I am getting better at these things ;-)
Cheers
Val
edit : Open Office or Libre Office will do the job ;-)