Clinton's comment that you highlighted isn't at all incompatible with Mc_Big_G's explanation. The Russian influence on the 2016 election was via use of advertising as a propaganda vector and compromising email servers, not compromising the voting mechanisms or machinery directly.

No reason to risk the blowback from changing even a single vote if you can instead just convince millions of Americans via micro-targeted advertising that a con artist who lives in a gold-plated room atop his skyscraper is somehow their savior from sclerotic government, or that the same con artist is less corrupt than his political opponent (having no political track record in which to generate a history of corruption).