In short, AXP Review is a "dating service" between readers and authors. These are real people, not employees. These are not paid reviewers (that would be against Amazon TOS).
Ultimately, what you want to do is be self-sufficient and have a team of people you email with each release---people you can count on to read your new release and review it shortly after it goes live.
With AXP, your book is promoted to readers, and you can ask them to join your team, too
That means you can use the service:
What Will I Have to Do?
Anything Else I Should Know?
WHAT ABOUT AMAZON?
Amazons Review Guidelines (10/3/22) state: https://www.amazon.com/gp/help/customer/display.html?nodeId=14279631
Compensated reviews
Reviews should reflect your honest opinion. We don’t allow reviews that are created, edited, or removed in exchange for compensation. Compensation includes cash, discounts, free products, gift cards, and refunds. Some common examples of what’s not allowed:
Exceptions:
That means you can still give away free copies in the HOPES of getting reviews, but you can't give away free copies "in exchange for a review."
Can I give free books to reviewers using the AuthorsXP downloading system if my book is in Kindle Unlimited (KDP Select)?
Amazon is a tad vague in this area. You can find all kinds of quotes on websites from other people---some authors report they were told directly by Amazon employees that it was fine to give out review copies while in KDP Select --- there are cut and copied quotes from past iterations of Amazon's site that imply it is okay if the book is shared by email and for the purposed of 'improving or proofreading ...'
If you want to be safe, don't give set up a page where hundreds of people can download the book for free. You CAN gift your book to reviewers through Amazon. Since you get 70% back, it only costs you a fraction of the cost in the end. Just use this button on your book's page. This will also make the reviews you get verified!