Why would you go in there?

Are these people you know who legitimately think you’d be a good fit?

I had assumed you knew them and they would help you. But from this comment it seems you may not actually know them.

They’re 100% not going to take you into any sort of back office and sit down to help you while on the clock regardless.

But if you actually know them and they’re actually saying you’d be good at it and should apply, then asking if they can take a look at your resume and give you some advice is a pretty normal ask for friends.

If you don’t know them, then Google what kind of resume the Post Office wants yourself.