Hi there, @INGT ...

When you are trying to submit your assignment, do the assignment details display the acceptable file types similar to this screen?

When you say that your instructor has the word "word" in the "File Types" area, is that what you are referring to?  If so, then your instructor has configured part of this assignment incorrectly.  Your instructor should be listing the file extensions (doc, docx, pdf, rtf, etc.) and not the actual software used to create those files.  And, I'm not sure why he would only accept *.doc files...as it's more rare now to see that file extension with Microsoft Word documents.

This is the Guide that your instructor would need to use: How do I create an online assignment? - Instructure Community (canvaslms.com)  Specifically, have your instructor look at the example under the heading "Restrict File Types" near the bottom of the Guide.

I hope this will help a bit...and hopefully you'll be able to speak with your instructor about allowing the proper file types for the assignment.  My guess is that your fellow classmates are having the same issues you are.  Good luck!