If you read Mueller's report starting on page 41 you can see just how complicit WikiLeaks & DCLeaks were in dissemminating the stolen information at key times during the election. You can also see just how involved Assange and WikiLeaks were with Trump Jr. and the various arms of Russian intelligence who did the hacking. Assange planned and manipulated information for maximum affect against the Clinton campaign who they were adamantly against.
WikiLeaks, and particularly its founder Julian Assange, privately expressed opposition to candidate Clinton well before the first release of stolen documents. In November 2015, Assange wrote to other members and associates of WikiLeaks that " [w]e believe it would be much better for GOP to win ... Dems+Media+ liberals would [sic] then form a block to reign in their worst qualities. . . . With Hillary in charge, GOP will be pushing for her worst qualities., dems+media+neoliberals will be mute . ... She' s a bright, well connected, sadistic sociopath."
Assange and WikiLeaks were responsible for pushing the Seth Rich story even though they knew that it was untrue. They insinuated that the dead staffer was an informant for WikiLeaks. They went so far as to off a $20K reward for information leading to a conviction.
WikiLeaks times the release of the stolen information for maximum affect e.g. after the Hollywood Access tape release.
The Ecuadorian Embassy's hiring of 3 outside security firms and the subsequent release of video showing Russian cutouts providing technical expertise and delivering information on multiple occasions during Assange's stay there is but more proof of the collaboration between Assange, WikiLeaks, and the Russian efforts to secure a Trump win. (Who lets a hooded man into the lobby of their embassy to deliver information to Julian Assange?)
The report also discusses Trump Jr.'s contacts with WikiLeaks and his efforts to secure and pass on information that would hurt the Clinton campaign. He in one instance is directed by a WikiLeaks surrogate to provide Trump who was on the campaign trail with a web address, that Trump can then mention at various campaign stops which provides stolen email information.