Membership in the HJ was compulsory once the Nazis consolidated their power. The problem was that if the kids didn't join they were expelled from school. Joseph Ratzinger's headmaster filled out the paperwork for him and sent it in, telling him that he would cover for him and he wouldn't have to attend meetings.
The headmaster did this largely because Ratzinger's father was rather too publicly opposed to the Nazis and suffered a good deal of persecution on account of it (the family had to move to a different town because of threats against the father).
And he also had a cousin who was mentally disabled and was taken away for "medical treatment" by the Nazi regime - shortly thereafter his parents were told he had died of some disease, actually he was one of the victims of a systematic program of murdering the mentally and physically "defective".
It's absurd for these newspapers to bang the drum about supposed Nazi sympathies on the part of the Pope.
It has its roots in the traditional British anti-Catholicism, which in turn has its roots in politics, not religion. Read almost anything by Charles Kingsley & you'll see what I mean.