With all of our plans, you can share a canvas with as many people as you need and they can comment to leave feedback as a guest with just their name and email. This doesn't create an account for them and they don't count towards the users on your team.
The functionality available to a user from a guest is that an internal team member has access to the team dashboard, team canvases, can create, share, delete, organize canvases, post and view private team comments, set feedback deadlines, access different integrations (Adobe, Trello, etc.), and export comments.
The functionality available to guest reviewers or non-team members is being able to leave comments, and also see and reply to other visible comments