The current official framework requires a nonrefundable processing fee, vetting and then a gift to the government. The applicant must be eligible for lawful permanent resident status, admissible, and have an available visa. A successful applicant receives lawful permanent resident status as an EB-1 or EB-2 visa holder. Re-verify every term before payment.
Read the official description, then read it again
The honest answer to what it requires is that the requirements are what the official material says they are on the day you look. The framework is recent, it was created by executive action, and its operating details are published by the programme itself rather than derived from decades of case law the way the older categories are. That has two consequences for anyone in Erin thinking about it.
First, secondary descriptions age quickly, so a summary written months ago may no longer be accurate, and advice should be traced back to the official page and the executive action. Second, the absence of a long statutory eligibility test does not mean the absence of conditions: vetting, documentation and payment arrangements are all specified, and each of them is capable of being changed. The practical discipline is to write down what the household is trying to achieve, check the official terms against that objective, and re-check them immediately before any money is committed rather than at the point the decision was made.