You won't get any correspondence from the IRS about your tax return unless there is a problem with it. Otherwise, the only mail you will get from the IRS is a check for your refund, if you requested to have it sent by mail.
For the FAFSA use the information on your copy of the tax return that you filed. You don't need anything from the IRS. You should always save a copy of your tax return when you file it, either on your computer or on paper. But if you don't have a copy, see the following FAQ.
How do I get a copy of a return I filed this year in TurboTax Online?
