They did make an agreement with the German right to get Hitler appointed chancellor... but that was basically a “you conservatives are going to lose either way, do you want to lose to us? Or to the communists who will murder you?” type of thing.
It was a personal vendetta between Von Papen and Von Schleicher.
I must admit that the German right had underestimated Hitler.
Furthermore, he had, before seizing power, pulled the wool over the eyes of many conservative monarchists, by dropping hints that he was planning to reintroduce a constitutional monarchy...
Lies. But, as they say, hindsight is 20/20.