Download the trial of Filmlight Daylight and use that to transcode from ProRes RAW to EXR might be the simpler option.
If you want to use After Effects to output ACES CG you will need to install Open Color IO. The AE plugin is available here:
If you follow the quick start guide (page3 in the manual) it is simple enough to install.
Once you have it working change Project Settings>Color>32 bits per channel and Working Space>None
Go to your comp and add the OCIO effect Effect>Utility>OpenColorIO to each footage layer
In the Effects Tab set OCIO up as follows:
Configuration>aces_1.0.3
Hit Convert and set the following settings:
Input Space>The colour space of your camera
Output Space>ACEScg
Hit Display and set the following:
Input Space>The colour space of your camera
Device>ACES
Transform>RAW (If you want to preview what your comp will look like in REC709 select it from the drop down menu. Do not use REC709 when you render though)
Render out as 16bit EXR and we should be good to go