Apparently there are two sets of site owners--the first batch got arrested, and then someone else continued to sell material. (More info about the press conference, and timeline)

For judging if the purchaser did something criminal it is irrelevant how the photos were made. It is only relevant if they were child porn, whose purchase and possession is illegal, or if the photos were merely showing naked children, without any sexual behaviour or focus on genitals. The possession of the latter is legal in Germany. And: not "legal". Legal.