I'm trying to make it so that untrusted (default) group members cannot claim at all, and regular members (promoted) can.
I scoured the issues page trying to figure out how to do it, but what I found didn't work.


While troubleshooting this I ensured that "Bonus Chunk Claims" were set to 0 both in the default player config and in my test subject's config. They were still able to claim as many chunks as they liked!

I would deeply appreciate if you could let me know what I'm doing wrong and provide me with a solution! ^_^
Here are my config files. Link expires in one week.

That's not the right way to set a node to a number value. You need to set it as a meta value, not a permission. For some reason I don't think the browser UI you're using makes it easy or clear that it even exists.
You can do it easier using in-game LuckPerms commands.
It will then appear on this UI as "meta.xaero\.pac_max_claims.1500" or something similar.