group offers diversity inclusion consulting, whatever that means

It usually means ensuring a lot of small details. For example if you have a native american character, they'd make sure you do not randomly pick a culture that doesn't fit what the character does or their background, that you don't show some non-native stereotypes, that you don't idolize them like in stories unless your specific story calls for that, etc etc.

You're supposed to work with consulting companies like these when you don't have people who can judge this on your own team, because it's so easy to get so many details wrong. Of course it'd be easier if your team already knows how to do it, sure. But if you can't, then it's the right step to get someone external who can help you not make a joke out of a character. Again, unless they're suppsoed to be a joke.