In a large living area, position the machine centrally where air can reach it from all sides and set the app to auto at about 50% humidity. Because the machine is oversized for a single room, it will reach the target quickly and then cycle off, which keeps running time and noise lower than you might expect.
For whole-house damp, a landing or hallway is the usual spot, with the doors between rooms left open so air can circulate. The machine works best when it can move the humid air from every room past the coils, so it needs to be somewhere central. In very large homes a single unit will not reach distant rooms.
For laundry, use the laundry mode in a closed room and run the high fan speed. A large load of washing dries in a few hours, and the 40 litre capacity means the machine keeps pulling water out even when several airers are in use. Connect the drain hose, as 5.3 litres of tank fills quickly at this rate.
In a bedroom, the machine is more than you need. If you do put it there, use the low fan speed and the schedule so it works before you sleep. The high speed is not suitable for light sleepers.
The 40 litre rating is measured in warm, very humid conditions. In a typical UK room at 15-20°C the real figure will be lower, so judge the machine on its ability to cover a large space rather than on the headline number. Empty and rinse the tank, and wash the filter every few weeks, drying it fully before refitting. The unit is heavy, so use the wheels and handle and avoid lifting it when the tank is full.