Welcome to our community!
Having a free subscription and using the API are two different things.
There used to be free credits given to new account creators, but that is no longer the case.
It is true that there is a free tier on the API platform, but you can’t actually do anything without paying for credits.
At the very least, you need to pay for credits to start using it. Charging $5 worth of credits should put you in Tier 1 (there may be a time lag).