The official program site describes a gift to the U.S. government plus a processing fee, applied for through the government's own process, with eligibility and screening terms set out on the official page and FAQ. Those terms should be read directly and re-checked before any money moves.
The requirement is defined by the government's page, and only there
Unlike TN, L-1 or E-2, the Gold Card is not described in a long-standing statute and regulation that this site can paraphrase with confidence for years at a time. Its terms live on the official program site and its FAQ, and the government can revise them. The elements the official page has described are a gift to the U.S.
government, a processing fee, an application through the official channel, and screening of the applicant. Yusuf should read that page himself, save a dated copy, and treat any difference between it and what an intermediary tells him as a warning. He should not assume that the gift is refundable, that it guarantees a particular outcome, or that it is exempt from the admissibility rules that apply to anyone seeking status in the United States.
If he has questions the FAQ does not answer, they go to a licensed U.S. immigration attorney, not to the person selling the service. This site does not vouch for any intermediary.