“Some have taken it as far as to suggest that most of his theories were made up.”
Of course they are “made up”. All theories are made up by someone. Then you test them to see if they are right. That’s how science works.
But in Freud's case, the claim is that a lot of his theories were never tested or proclaimed factual without any real, or at the very questionable, backing. Also known as "pseudo-science."