Citizenship Eligibility Document

Hey! Im an undergraduate student at NYU going into my sophomore year. I’m on a full ride academic scholarship here that I received. Recently I spoke with the financial aid office at NYU was told that due to my green card expiring before the school year begins, my financial aid package was going to be withheld. Apperantly they aren’t going to give any of my financial aid package until I renew my green card and show them the new card. However, I’ve been reading up that I can get a temporary I-551 stamp that proves my legal status as a permanent resident. Does anyone with some sort of experience with this know if this stamp is enough to prove my eligible non citizenship status to receive my financial aid? If so where and how can I obtain this stamp? I’m in the process of getting my citizenship but that is going to take months and by the time I’m approved, the school year would be well underway and I really do not want to fall behind an entire year and lose my scholarship. Even applying for a renewed green card would take long and I wouldnt receive the new one on time to provide it to NYU.