Why was Lark auditioning if they were not looking for a Black girl??

2 reasons
if they didn't allow her to audition they might open themselves to bad publicity or even a lawsuit based on racial discrimination.

plus, she was an impressive young actress, maybe one of the producers wanted to give her a chance (it seemed to work)

I think the character was intended to be a rich caucasian Jewess but they were open to whomever auditioned and it just so happened Lark was better so they patterned the character to fit her when she won the role.

When theres no more room in Hollywood, remakes shall walk the Earth.

[deleted]

You can audition for anything really, even if you're not what the casting call asked for...

A bit of the old ultraviolence...

In addition to what everyone else said....

Lark probably read the description of a "spoiled, rich, fashion-loving girl with wealthy educated parents" and thought, "I could play that."

The producers and creators had in a mind a character like "Rachel Green" from Friends. In their mind, they were picturing a high society white girl--they never publicly announced "whites only" or "we're only casting this part as a white girl."

Also, many actors and actresses trying to make it in Hollywood will audition for anything, even if they think they have no shot, like a 28 year old auditioning to be a high school student. You may as well go for it!

So I think that Lark saw the description and decided to go for it.

Laws probably require them to let her audition, but there are no laws saying a show creator has to select them.

It's most likely that the script didn't specify the race.

Given that she got the job, it's a good thing that she did, eh?