To view the comments for a requirement version, click on the comment icon in the right side vertical panel.
To view the comments made during a review, click on the Reviewer's tab in the right side vertical menu, and then on the comment icon within that Reviewer's tab. This will show all the comments made during the review for that requirement version.
Users will need to have project permissions to view the requirement to perform this action. Depending on the settings of the user's project permissions, they may be able to view all the project requirements or just a subset of them. Users added to a specific requirement as a contributor or reviewer will be able to view it.