I don't know how that specific site works, but technically I would consider it published, you have made it available to the public.
By doing so, you have potentially damaged their sales and their marketing. Consider for a moment if your work is excellent and compelling, and the free availability makes it read by hundreds of people. Wonderful, right?
No, it isn't wonderful. See This Article on Publishing statistics. The average book sells about three thousand copies in a lifetime, and may sell only hundreds in its first year. First books are likely even less. So by making it publicly available and free you may have given your book away to most of your audience that might have bought it. You've poisoned the well.
"Previously Published" is about its availability to the public, not whether you got paid for it. It is not published (available to the public) if you give paper or electronic copies to people you trust to not send it around. If you post it on a website for strangers to read it, talk about it, praise it, or condemn it, you should tell any agent or publisher or you are lying to them, and they will then be influenced by what happened there, and neither outcome is good.
If people loved your book and told everyone, their sales are diminished and your "newness" factor is gone. If people called your book amateurish and poorly written, the agent or publisher may change their enthusiasm for it.
My suggestion would be to write something else, a short story or scene or something that has nothing to do with your story, but is written in your style with your style of dialogue and exposition. Ask people to review that, and try to apply their criticisms to your book. I should think people are more likely to review a shorter piece anyway, and then you give away a week or two of work, not a year or more.