Intuitively, I would suspect that it's not enough... Maybe you can get some tips from the manufacturer of the system? Our neighbors solved the "problem" of controlled residential ventilation in the attic with a concrete ceiling (bungalow). The construction company had already implemented the same configuration once, but with a wooden ceiling, and the client was not 100% satisfied.
What I originally wanted to say: The device is relatively large/powerful and operates at a lower speed than smaller sized devices. For a concrete ceiling, of course, it is already too late.
The feedback from reassures me for now. In our case, it is supposed to look like this from top to bottom:
- Controlled residential ventilation main unit
- Rubber mat
- 22 mm OSB boards as storage floor
- 200 mm collar beams with 200 mm rock wool between the collar beams
- Battens
- Counter battens
- Cladding (probably one layer of OSB and below that another layer of gypsum board)