I screenshot a “start building” flow you might see in the platform.openai.com site in the post linked below that is supposed to get a new account some free uses of select models, an undocumented quantity or capability of “free use” except by casual mention on the forum.
I expect this is a button and final “free” offered and successful if you have a completely original API account that was just setup, never offered an API trial credit (as any ChatGPT signup would be given up to program termination over a year ago), a new profile not triggering many possible guards against exploitation beyond simply having a common phone number or active sign-in credentials from providers or a cookied-up browser.
Or simply if you look like a “lead”.
It may be then that it is only successfully set up if you continue through completely, adding a payment method anyway, one that is unique to the platform. Consider Stripe as payment processor is also aggregating cards and personal information and business info passed by OpenAI to be easily used against you for detection of prior engagement. “Free tests but be prepared and willing to buy credits”.