Trump absolutely knew. A high-level campaign adviser wasn't working in a vacuum to establish these ties and collude with the Russians. We're not that stupid, Trump!

"The adviser, George Papadopoulos, has pleaded guilty to lying to the F.B.I. about that conversation. The plea represents the most explicit evidence that the Trump campaign was aware that the Russian government was trying to help Mr. Trump and that the campaign was eager to accept that help.

As part of that effort, the Russian government hacked Democratic accounts and released a trove of embarrassing emails related to Mrs. Clinton’s campaign. The Trump campaign has repeatedly denied any inside knowledge about that." - https://www.nytimes.com/2017/10/30/us/politics/george-papadopoulos-russia.html