Illegal and anti-democratic aren't always the same thing. You can certainly be one without the other. Though to be clear there have been allegations of outright illegal activity by the Clinton campaign and the DNC as a whole during the 2016 election, but the specifics are fuzzy in my memory and that's not what you're asking about so I won't attempt to address it further here.

Here's the first article I read through after a quick search to find a source for you. If you don't like the source I'm sure you can use the timeline and references it contains to find something from a source you prefer.

https://www.politico.com/magazine/story/2016/11/hillary-clinton-2016-donald-trump-214428/

Here's a couple relevant snippets:

So to take [Jeb] Bush down, Clinton’s team drew up a plan to pump Trump up. Shortly after her kickoff, top aides organized a strategy call, whose agenda included a memo to the Democratic National Committee: “This memo is intended to outline the strategy and goals a potential Hillary Clinton presidential campaign would have regarding the 2016 Republican presidential field,” it read. “The variety of candidates is a positive here, and many of the lesser known can serve as a cudgel to move the more established candidates further to the right. In this scenario, we don’t want to marginalize the more extreme candidates, but make them more ‘Pied Piper’ candidates who actually represent the mainstream of the Republican Party,” read the memo.

Eleven days after those comments about McCain, Clinton aides sought to push the plan even further: An agenda item for top aides’ message planning meeting read, “How do we prevent Bush from bettering himself/how do we maximize Trump and others?"