Ah, I know this is a pain, but by default o3 is only available to developers on tiers 4–5.

If you're in tiers 1–3, you can still get access - you just need to verify your org with us here:

https://help.openai.com/en/articles/10910291-api-organizatio...

I recognize that verification is annoying, but we eventually had to resort to this as otherwise bad actors will create zillions of accounts to violate our policies and/or avoid paying via credit card fraud/etc.