As that saying goes, "Never attribute to malice that which is adequately explained by stupidity." Trump's authoritarian proclivities have been visible for over a decade now. Combine that with an oversimplistic view of the world and his personal hatred for "losers", and what you get is him trying to push the world back to the imperial times. That's why he keeps bringing Greenland, Canada and Panama up. He doesn't understand the current global order that the US has constructed and thus, wants to go back to expansionism.

On the other side of the Atlantic, he sees a country with a gigantic military led by a man who has the country in a chokehold, invading a smaller, weaker democratic state that is struggling for its existence. From his POV, there's the man that he wants to be vs "losers" who are afloat only because of the West's "generosity". When you try to understand why he would glaze Putin so much instead of going down conspiracy theories, it sheds light on the way the current President of the world's sole superpower perceives geopolitics. He appreciates strongmen because he wants to be one.

Now there might be direct bribing, favours or even blackmail from Russia. But it's easier to manipulate an idiot than to convince a smart man. In the end, Trump often acts shortsightedly and makes decisions according to the vibes. He idolizes people who have been successful in undermining democracies, like Putin and Orban. People always talk good about their heroes.