To pit citizen against citizen and neighbor against neighbor by installing the most divisive and chaotic administration in history.
Perhaps even to the ends of causing civil unrest in the US. Let's not forget that the Russians have been found to be active in the California succession and Texas succession movements. The biggest win possible for Russia is to break up the union and destroy the Republic. Nothing less.
That is why this is treason on the part of tRump. Who has not yet declared his determination to protect the United States from Russian interference.

Creating chaos weakens the US. (It's working, right?) In a win-lose calculation, if the US is weakened, Russia is relatively strengthened.

His grudge against Hillary has its basis here:

"In December 2011, Vladimir Putin came closer than he’s ever been to losing his hold on power. His decision that year to run for a third term as Russia’s President had inspired a massive protest movement against him. Demonstrations calling for him to resign were attracting hundreds of thousands of people across the country. Some of his closest allies had defected to the opposition, causing a split in the Kremlin elites, and Russian state media had begun to warn of a revolution in the making.

At a crisis meeting with his advisers on Dec. 8 of that year, the Russian leader chose to lay the blame on one meddling foreign diplomat: U.S. Secretary of State Hillary Clinton.

“She set the tone for certain actors inside the country; she gave the signal,” Putin said of Clinton at the time, accusing her of ordering the opposition movement into action like some kind of revolutionary sleeper cell. “They heard this signal and, with the support of the U.S. State Department, started actively doing their work.”

From - http://time.com/4422723/putin-russia-hillary-clinton/

Mueller's indictments indicate that Russia/Putin not only supported Trump but also Bernie and Jill Stein. In other words, and this will sound familiar, anyone but Hillary.

Trump loves borscht soup

Clinton, in particular, had worked against Russian interests in the Middle East, North Africa.