I suppose reasonable people could argue both for and against what constitutes collusion, and especially whether it is illegal or not, but I think that the Russians hacked the DNC is pretty much established fact - if you don't accept that, then you're drifting into conspiracy theory area. The indictments of the Russians specifically mention the timing. The hacking occurred after Trump's infamous campaign call for them to find Hilary's missing emails. The results were released through WikiLeaks which Trump refereed to many times during his campaigns.