I would not recommend rendering ACEScct to EXRs. Not only is it non-standard (which doesn’t have to be a problem, as long as everybody involved knows you are using a non-standard approach) but it is very inefficient use of the EXR code-space. ACEScct will produce values constrained to the 0-1 range (actually for camera imagery it won’t get anywhere near 1.0) but less than a quarter of the available EXR code values represent the 0-1 range, with the rest used for negatives and >1. EXR is designed to hold linear data. ACES2065-1 (linear AP0) is the ACES standard, although some people do use ACEScg (linear AP1) for internal interchange.
Have a look at the ACES VFX Quick Start Guide.
Regarding the choice of linear AP0 or ACEScc(t) for LUTs in Resolve, as long as the LUT you use is built for the correct space, the choice is up to you. Bear in mind that LUTs for linear data need a shaper, as a simple cube does not have the required precision.