You qualify for federal education loans simply by being a U.S. citizen (or eligible non-citizen) enrolled at least half-time at an eligible college. You must complete the Free Application for Federal Student Aid (also known as the FAFSA). You’re not eligible for federal aid if you have federal loans in default.
A parent’s credit history is reviewed when applying for a PLUS loan, but only to determine if there is a history of late payments or other adverse circumstances.
For most types of loans (such as an auto loan or a mortgage for a house), your financial ability to repay the loan is closely considered by the lender. That is not true for federal education loans. You are the one who must decide how much you can afford to borrow.