Hey! I fixed reviews so the example should work now and pushed out a change to the developer site to fix a broken example I noticed.
It looks like the error on that page is asking you to create an API account and authenticate. So maybe not an error in the API itself, but an oversight in documentation?
Once you create an account you will also get an error about needing a business_id. But using the pre-filled example or sample above it won't work.