I need to create an assignment where students can upload their research papers, but that everyone in the class can have access to them and download them.
Let me ask you this:
Personally, if I were taking a class and my instructor wanted me to read everyone's research paper, I would heading to the door.
Can you create a graded discussion to suit your purposes? Everyone can see the replies and attachments can be made. Making it graded is possible, so If you wanted to grade their submissions you can.
I would look into discussions for doing what you want.
Here is the instructors guide list of discussion help files
I thought about the idea of a graded discussion, too. However, if I were a student and confronted with a discussion of nothing but research papers (or links to research papers), I'd pull my hair out.
I have taken a course in which the instructor created "showcase" pages for our work. She had a module with a page for each student. The pages were editable, so we could each present our individual project. That worked well in terms of the class being able to see all of the projects. The caveats are that pages cannot be graded, and that anyone could potentially edit a classmate's page.
Again, this goes back to these fundamental questions: