He hated the Weimar Republic as much as he Nazis. The conservatives wanted a new state in which all the powers were concentrated in the hands of president and parliament would be diminished or even abolished. Some even wanted the Emperor back. For these goals, they thought they could use Hitler, but it was the other way around.

Socialists in the country were taking over, this was not ideal for the traditional Conservatives such as Hindenburg. The nazi party was not that popular and only got a majority vote in Schleswig-Holstein. But although not popular, they had alot of support from young energetic people. Hindenburg, and the other traditional conservatives, thought if they gave Hitler a position in the government he would crack down on the socialists. Hindenburg surrounded Hitler with the traditional Conservatives in cabinet positions. TLDR he thought he could control Hitler and use him to crack down on socialism.

Sources was from Paxton and the anatomy of fascism mostly and a college curriculum.