Amazon says the Customer Reviews tool is available to sellers with a Professional selling account who are also Brand Representatives for brands enrolled in Amazon Brand Registry. Amazon gives that eligibility requirement directly on the Customer Reviews tool page.
What account type does Amazon require?
Amazon says on the tool page that sellers need a Professional selling account to access Customer Reviews.
That means the tool is not available to every seller account type.
What brand access does Amazon require?
Amazon says on the same page that the seller must be a Brand Representative for a brand enrolled in Amazon Brand Registry.
Amazon also says that if a seller works for an enrolled brand, the rights owner or another administrator can assign the Brand Representative role.
Why does that matter?
This eligibility requirement is part of why the Customer Reviews tool should be understood as a brand-management feature, not just a generic seller utility.
Amazon ties access to both selling-plan level and brand-registry permissions.