Russia has its own troubles, and I'm not going to judge Putin one way or another, he has an air of a tyrant, but Russia doesn't have the social society needed to form a fair and free democracy, the Russian "Family" of oligarchs is always at bay, and so maybe Putin is a necessary ruler as it stands.
But I think one thing that is obvious is that Putin sees foreign relations as a very competitive ground, and so destabilizing the US is to the benefit of Russia, as they see the US as a major blocker for Russia's expension in the international sphere.
As for Americans, I don't think they hate Russians. What it is is they love their freedom, and they hate anyone who might be working to take it from them. That's why there are only two options, either make the whole world free, or continue to have the strongest military in order to protect their freedom from others. And I respect that, since I value freedom myself.
Russia, as you must know, isn't really promoting free and fair democracy right now. So American see them as a threat to free society and their freedom.
And Russia might be wanting to continue its expension of conquests to its former Soviet partners, so after expending in Ukraine and Georgia, they might want to move in on others. But the biggest blocker for Russia to expend its military conquests is NATO, and that's why destabilizing the US is to the benefit of Russia. Or having a president like Trump which didn't value NATO or helping its allies, that also benefits in this case.
Also, there is a lot of evidence that Russia meddled in US elections. Neither you nor me will see it first hand, so if you don't trust the FBI, the US House Committee of Intelligence, the Special Counsel of Mueller, and the Republican independent intelligence investigation, well there's nothing more you can do. But all those investigations reported the same finding, that there was systematic interference from Russia, attempts at hacking election systems, hacking of elected official computers, leaks of their data (like Hilary's emails), social media troll farms, etc. What there wasn't was enough evidence that Trump collaborated with them on this.
Another good reason isn't so much pro-trump as being against Clinton, since the Clinton are responsible for adding to NATO former Soviet allies like Poland, Hungary and the Czech Republic. And that was always seen like a slap in the face by Russia, which made them wary of the US.
Some people even blame that move by Clinton for the bad US-Russia tensions we have today.
Hopefully that gave you enough context why Russia would want to interfere in the American elections, as well as simply in their general cultural and social spheres.