Is ventilation/drying after installing screed/interior plaster sensible?

and the construction site is properly heated

how else without a construction dryer? Underfloor heating on fresh screed? (if it’s even connected yet) But on milder days you could leave the windows permanently tilted open, or would that be totally stupid? (apart from rain etc.)

how without a dehumidifier?

With fan heaters. For fast screed, for example, you can already start the floor heating's heating program after 3 days.

Windows on tilt when you heat inside: The reveals are cold and warm moist air could condense there, plus more heating energy is needed.

If you do not heat inside, in my opinion tilting the windows still does not help much. It could also lead to rewetting, for example if it is warmer outside than inside at noon.

Is there a difference between a dehumidifier and a fan heater? If not, I do not understand your answer "With fan heaters" to my question "how then without a dehumidifier?"

When I research both terms, I would say they are used synonymously by many providers in this field.

For me, both terms have been synonyms so far and refer to electrically operated devices that generate heat and blow this heat out of the device with an additional fan, thereby releasing it into the environment. Presumably, there are devices whose fans actually create "winds" or airflow and those that are only supposed to transport the heat out of the device enclosure.

A fan heater produces warm air. A [Bautrockner] also removes water and collects it in a container or drains it into a drain.