Or if you feel like sending them an example of your best guess.
Lets assume this EXR footage is Linear Rec.709
I would tag the footage as scene-linear 709/sRGB
and then output a ProRes4444 (12-bit) making sure you use LUT in the export window and select ViewTransform and hit Edit.
By saying it was Rec.709 we can just apply a 2.4 gamma curve to the EXR footage using these settings:
