He was definitely green - more used to breaking into small businesses than high-security facilities - and his professionalism was lacking, but at the very least he was enthusiastic.
This is an overly long sentence to describe Kyle, which is okay once or twice, but be careful this doesn't become a consistency.
He tugged at his shirt.
It's ambiguous if this is Kyle or David, because the previous sentence was describing David talking about Kyle, and there isn't enough here to know if we should take it as a limited 3rd person perspective or as a 3rd person universal.
David asked. Like many hackers, she went by a handle rather than her birth name.
This is a bit clumsy.
"I've got the cameras, access control, databases, AD, everything. I'll have put their team out of a job by lunchtime!//"
Missed an italic.
"Come on!" Susan called impatiently. "One minute of your life is an hour of mine!"
I would recommend going against using adverbs if one can help it. Try to find stronger verbs instead.
. The walls were a plain beige that desperately needed to be repainted
This may not be clear what that looks like. Describing peeling or cracking would've been more effective.
He clumsily pulled himself up.
More awkward adverbs.
The guard glared at him suspiciously.
Yeah this could be tightened.
Overall this is a nice story that isn't particularly compelling in plot or stakes, which then relies on interesting interactions between characters and snappy prose to make it a fluid read. This is not very snappy prose, which makes the character interactions stilted or wooden occasionally.
