How Should I ask him?

I'm thinking that you are overthinking this.

It's a quick meeting. It's probably going to be a quick coffee. Send him an email or a text or call and ask where and when, as if you were going to meet a girlfriend. It's no harder or weirder than that. You have every right to know where you are going, etc.

Also - a suggestion - don't overdo it in terms of getting ready. If you're going to work afterwards, then wear your work clothes, whether it's a doctor's scrubs or business casual. Be clean and presentable (of course) and with no more makeup than you normally wear.

This does not sound like much of a date. It sounds more like a quick once-over. And that's fine. Don't project more onto it than it is.