You can decide if you want to manually assign partners or if you want Canvas to assign students.  

Anonymity:  Students take more accountability when they know that their name will show on their critique/review. 

Set up a secondary assignment to give students credit for performing a peer review.  This work is separate from the work they put into creating their draft and warrants compensation of their efforts.  

The first time you do peer reviews, you will want to follow-up carefully with how students performed during the peer review.  

After spending so much energy designing the peer review, we often overlook how we want students to use the feedback they receive or if they will respond to their peer reviewers.  Make a plan on how students will use the feedback and how they will respond to peers will give them a voice and give the feedback more meaning.  Create a way for students to show you they learned from the feedback and made revisions. 

A reflection activity is the final capstone to a peer-review activity.  This gives the student a chance to report back to you about their learning experience.  In a reflection, students have a chance to fully process the experience and draw meaning from it.  You will need to build a reflection in Canvas. 

Google Assignments and Feedback in Canvas

Another option is creating a Google Drive folder, sharing the folder with your students, and having them turn in their work for feedback via Google Drive.