"could you link me to one?"

Sure; here's how you do it. Google:

RRC 2021 eligibility

because you are asking about the Credit, not the EIP which was advanced projection Payment.

You get this result:

https://www.eitc.irs.gov/other-refundable-credits-toolkit/what-you-need-to-know-rrc

It tells you:

"Who is an eligible taxpayer for RRC?

       An eligible taxpayer must:

• Have a Social Security Number issued by the Social Security Administration before the due date of your tax return (including extensions).  (Exceptions apply for members of the military and their spouse).
• Be a U.S. citizen or U.S. resident alien. For more information see Publication 519, U.S. Tax Guide for Aliens.
• Not be a dependent of another taxpayer's tax return for tax year 2021."

The same as your Program is handling it.

On the Left Side of that page, you see other IRS links. Such as:

https://www.eitc.irs.gov/partner-toolkit/hot-topics-for-our-partners/refundable-credits-news-and-upd...

Now you should be able to research for yourself.