Thank you for the additional notes!
The situation is that you want to apply a rigid covering with ceramic tiles onto a floating cement screed.
Certainly, screeds also dry without underfloor heating, but as long as the screed is not a special construction (these include all screeds not covered by standards, thus also those with so-called accelerators, i.e. screed additives), the load-distribution layer cannot possibly have reached its equilibrium moisture after about 2 weeks.
For special constructions, always follow the manufacturer's instructions, but CAUTION: general advice like "ready for installation after 7 days" is misleading because only the constructional framework conditions are decisive for the drying of a screed. And no manufacturer knows these!
The note about the "diffusion-open adhesive" is outright nonsense and shows that the construction manager in this case does not know the building physics background nor DIN 18365 (or also DIN 18356).
If you install too early, the screed will be hindered during post-drying from neutralizing its stresses by length minimization. This would preprogram floor damage that would become apparent after about 1 to 1.5 years through wild cracks in the rigid tile covering.
A responsible tiler will do his CM residual moisture measurement and will definitely not lay tiles at a value > 1.8 CM-%. Not even partially, here or there.
Regards: KlaRa