So this should be the website for it but for some reason the site will not load at all (Had several international folk try, so it isn't just me!). Not sure what is going on there. That said though, there was a companion book published in 1996, and which is available in English translation as The German Army and Genocide: Crimes Against War Prisoners, Jews, and Other Civilians, 1939-1944. I would, however, stress that it is hardly the be-all, end-all resource on the topic. It is a very good one in terms of its extensive use of photographic evidence, including several hundred images, drawn extensively from the exhibit itself, as well as highlighting various primary source documents.

But there are many other quality works out there which cover the topic.

A few standout examples Omar Bartov's Hitler's Army (he is also the author of the introduction of the above), Wolfram Wette's The Wehrmacht: History, Myth, Reality, Soldaten: On Fighting, Killing, and Dying, from Harald Welzer and Sönke Neitzel, and of course Willy Peter Reese's posthumous memoir A Stranger to Myself: The Inhumanity of War: Russia, 1941-1944. If it is specifically free, online resources that you are looking for, the subreddit FAQ, and also the Profile of /u/commiespaceinvader as he has covered the topic extensively