I don’t see an issue with asking questions.

Honestly even if you (hypothetically) don’t know what you are doing, it’s still better to ask than not to ask and mess things up (unless of course you can figure things out without asking).

It also depends what kind of things you don’t know. Are they in your job description? Are they skills related or procedures related?

Like a math teacher doesn’t know math (ouch) or a math teacher doesn’t know when something is due at a new school or doesn’t know who has the key to a supply closet (perfectly fine).

I assume your degree (or other training), resume and questions on the interview already revealed your skills. I assume you were truthful. They wouldn’t hire you if you had no skills. So if these are procedural questions, then it’s only normal for new employees not to know stuff. So it’s perfectly ok to ask.