Can user upload Word docs into fillable form fields?

Hi,

I have created a fillable form in Adobe DC Pro and have saved a reader enabled version.  I have three locations in the form where the user can upload supporting documents for the project they are reporting on.  I want them to have open options for which file extensions they can attach.  When I test the form on my computer, I am able to upload files created in Word, Excel, etc. as well as image and pdf files.

However, when my co-worker tests the form from his computer and clicks one of the file upload boxes to insert image or word files, he only has two options: image files (.jpeg, .png, etc.) and .pdf files... his native Office files don't even appear as options to upload.  Is this related to the version of Reader he is using?  He can upload files, just not Word files.  Is there a way to fix this (ideally I want Office and Pages users to be able to upload their native files (for those who struggle to save something as a pdf!).  Can someone help?  Thanks in advance!