ProEXR 2.5 gets rid of the separate ProEXR AE plug-in, which has been merged into the main OpenEXR plug-in. That means AE now ships with the features in ProEXR AE, such as the ability to set up your layered comps for you, as well as export layered EXR files. To have AE set up comps for you, import your EXRs using AE's regular Import File dialog, and then tell it to Import As Composition, which is very easy to miss. Fans of the old File menu item can bring it back by editing their AE preferences file.
|Import As Composition|
The easiest way to get ProEXR 2.5 is to just start using the new version of AE. For people sticking with older versions, you can still download the plug-ins from the ProEXR site.