Many thanks for your tips, I wonder if a 10mm dowel will fit at all🤔
The bracket has to be retracted using the screws.
Too bad that neither information from the manufacturer is available or not simply 2 screws and dowels are supplied!!!

Good day
That depends on the nature of the ceiling. Wood is the easiest, as it doesn't need dowels. Be careful with plaster ceilings, they can crumble and this can look very ugly, in which case I would pre-drill with the finest possible drill bit and continue drilling with a drill bit of increasing size until the size of the dowel (diameter approx. 4-5 mm) is reached. Be careful when inserting the dowel, the hole must be exactly a hair's breadth larger than the dowel. Plaster is tricky!
A percussion drill with special drill bits is required for concrete ceilings. Otherwise, follow the same procedure as for plaster ceilings. Concrete is hard and rarely crumbles.
Have fun with the really great Lampe☀️

You are on the safe side with a 10 mm dowel and appropriate screws and drill bits, as the lamp already has a certain weight and is only fixed with 2 screws. However, an 8 mm dowel should also be sufficient.