Being asked to use "folks" in Australia was frankly bizarre. It's not a word anyone uses over there and would be considered a severe Americanism. Pretty sure that suggestion came from our Texas staff, not the Californians.

Depends on context:

> Hey folks, what's the status of that document?

Just means the people being addressed.

> Are your folks coming to dinner?

is, "Are your parents coming to dinner?"

Wiktionary lists both as definitions: https://en.wiktionary.org/wiki/folks#Etymology_1

I think your understanding is mistaken, or at least regional. While it can mean "parents" when used in the plural with a possessive ("my folks", "your folks", sometimes even "the folks"), in modern American English it's as commonly just a synonym for "people".

Using "folks" (especially in the plural) to mean people can be rather "folksy", though, and I wouldn't be too surprised if some textbook or dictionary mentioned just the "parent" definition. Did you learn it this way as a second language, or as a native speaker somewhere non-American?

Folks has been used to describe a group of people in the southern US for a long time. In pop culture it was used like that by Porky Pig at the end of Looney Toons with "That's all, Folks!" (i couldn't remember the how the stutter goes though)