What does this financial aid application priority date at UF means?

I applied to UF late January and was accepted April 2nd. I had filed FAFSA January fourth and in ISIS says that the university got it Jan. 20th. Now they are telling me that I might have missed out on additional aid because I was accepted after the March 15th priority date. On the financial aid website says that you should file your FAFSA before this date not get accepted by this date! Now because of this I might have to get private loans for about $8,000. Is this correct? Am just a little skeptical because the person I spoke to couldn't speak Inglish correctly. Some info please.