PxrCryptomatte is supplied as a Sample Filter plugin. As such the output for Cryptomatte is stored as a separate EXR file from your beauty or denoise outputs. Please note an OpenEXR is required to store the values correctly. See here for how to attach sample filters and how to combine sample filters. 

Layers

• nameName

• pathPath

• material

• Attributeattribute
  • user:__objectid
    
    
    
  • user:cryptomatte
    Image Added
  
  
  • user:myatttr
    Image Added

...