Yes there are basic eligibility criteria to receive student aid.
What is federal student aid used for?
FSA must only be used for educational purposes.
What amount of enrollment should I be in?
To get Direct Loan Program funds, you must be enrolled at least half-time.
Along with being registered with selective service at age 18-25 what are is another criteria?
You must be enrolled or accepted for enrollment as a regular student in a eligible degree or certificate program to get student aid.
How could I prove I am qualified to obtain a higher education if I don't have a diploma?
Did  you pass approved ability to benefit test if you don't have a diploma or GED?
Yes, I did pass the test..
Then you would be able to benefit from the Ability to Benefit alternatives.
Can I sign the form saying I am not in default on a federal student loan?