There is no feature in Canvas that allows any student in a course to access any other student's submission. To enable this, you must manually make one of the following setups:

Place a zip-file with all submissions in a module
Ask students to upload in a discussion

Place a zip-file with all submissions in a module

Students submit their file(s) in a regular assignment. When the deadlines has passed and students have submitted, you download all submissions as a zip-file from the assignment page.

Download students submissions.

Then upload that zip-file to a module (just as you do with any file). Now students can download the same zip-file and access any submission by extracting it.

Ask students to upload in a discussion

In addition to submitting in a regular assignment, you can ask students to also submit a post with their document attached in a discussion. Since replies to a discussion can be public to any student enrolled in the course, your students can access (and comment on) any submitted work.

An alternative to this option is to skip the regular assignment altogether and have students submit in a graded discussion only. That way, students won't have to submit in two different places. However, students must use the attach file option when posting (and not embed the document in the reply text). Otherwise you will not be able to display the document in SpeedGrader. It must then be downloaded.

Screenshot highlighting the attach feature when writing a reply in a discussion.