After WWI unfair treaties were forced on Germany but what was it that they were made to do/sign to get out of WWII?
I believe you need to specify between East and West Germany, they were handled very differently. The countries were not reunited until 1990.
Well, first off, the Versailles treaty and its character, especially with regards of fairness and it being forced upon Germany are things that are less clear cut than the traditional narrative would suggest.
Secondly, as for Germany post WWII, the experience of WWI, meaning of political groups in Germany using Versailles and the stab in the back legend to nurture revanchist sentiment lead first to a complete occupation of Germany in conjecture with a stop being put to all German political activity at first. Only in 1949 was German sovereignty restored in German Democratic Republic as well as the Federal Republic of Germany.
Generally, the FRG was treaty as the official successor state to the Third Reich and in that capacity several treaties were signed concerning restitution for the war (waved by some countries) as well as for war crimes and the Holocaust. With the socialist countries of Eastern Europe, the GDR was not really seen as a successor state thought the Soviet Occupation authority did indeed basically take a lot of industrial capacity from East German in lieu of restitution.
As for a treaty similar to Versailles, there is no such thing as an official peace treaty, but a treaty made in lieu of a peace treaty, the 2 plus 4 agreement or Treaty on the Final Settlement with Respect to Germany, negotiated in 1990 prior to German unification. In this treaty the former allies waved all remaining rights they had in Germany and fully restored German sovereignty, basically allowing reunification of the GDR and FRG to go ahead.
This is a very basic overview but to answer your question in a TL;DR answer: The main thing Germany couldn't do as consequence of WWII was unify.
Sources:
Christoph-Matthias Brand: Souveränität für Deutschland: Grundlagen, Entstehungsgeschichte und Bedeutung des Zwei-plus-Vier-Vertrages vom 12. September 1990. Verlag Wissenschaft und Politik, Köln 1993.
Heinrich August Winkler: Der lange Weg nach Westen. Band 2: Deutsche Geschichte vom „Dritten Reich“ bis zur Wiedervereinigung. C.H. Beck, München 2000.
Wolfgang Benz: Potsdam 1945. Besatzungsherrschaft und Neuaufbau im Vier-Zonen-Deutschland. dtv, München, 2012.
Christoph Kleßmann: Die doppelte Staatsgründung. Deutsche Geschichte 1945–1955. Vandenhoeck und Ruprecht, Göttingen 1982.