Adobe uses icc profiles in colour management workflow, not LUTs. So as to apply LUT you should utilise 'Apply Color LUT' effect.
Thanks for your answer!
So there's no way to work with a LUT in the custom output simulation?
My goal was to work without all those adjustements layers in "guide mode" on all the comp or the precomp...
If you can convert your LUT into icc profile, then you will be able to simulate your output that way. Otherwise you have to rely on Apply Color LUT (or LUT Buddy).
Very appreciate, thanks a lot!