Hi [Name],
I'm reaching out to you because [thing you have in common or noticed about them]. I'm interested in potentially pursuing opportunities in the [Department] team at [their Company], and I'm wondering if you're willing to share some thoughts on what it's like to work there and the culture? I realize that you have a lot going on, so I completely understand if you don't have the time right now and I wish you all the best!

Best, [Name]