This is a misrepresentation of the article. First of all, the lawyer who is investigating this did not accuse Father Ratzinger of being involved but turning a blind eye, which is circumstantial at best, and makes him an accomplice after the thought at worst.
In essence, the article alleges that between 1954 to the mid-90s the head of the choir was involved in the physical abuse and sexual abuse of over 200 children. The accused man is dead due to natural causes. However, Father Ratzinger and two others not named were in charge of a committee that oversaw many choirs, including this specific choir.
Father Ratzinger was not incriminated in this article as "leading a pedophile ring" or being involved in the abuse personally. His crime was not to interfere and stop the horrors perpetrated by others. May God have mercy on him for that.