If you are a refugee, asylum holder, Cuban-Haitian entrant, or victim of human trafficking...
To answer the question about the student's SSN:
You should use your SSN, if you have one. (In some cases, students with these statuses are granted SSNs, for example, so that they can work at a part-time job.)
Use your Alien Registration Number (ARN) if you don't have an SSN.
If you are a citizen of the Freely Associated States (Micronesia, Marshall Islands, Palau)...
... and don't have a SSN, you can complete the FAFSA® form without an SSN. When creating your FSA ID, click the box that says "I do not have a Social Security number.
I am a citizen of the Freely Associated States and I do not have a Social Security number."