They were not that close, they just drove in from Belarus and dropped some paratroopers with no support. That’s a good strategy for losing your best troops.
They also didn’t use a few days of bombing to soften up the targets. Ukraine was surprised but all of their equipment was intact. That’s like number one in any attack plan.
They basically underestimated the Ukrainians and thought they would just run away. Those paratroopers were very good but they are only scary to local police, not to a trained military. Without heavy support, they were sitting ducks at the airport.