Drill 70-75 mm deep holes at the marked points using a masonry drill bit (12 mm). Concrete ceilings are usually very solid, pre-drilling with a smaller drill bit (8 mm) is often helpful.
Then check whether the drill holes are deep enough. Test with an assembled heavy-duty anchor whether it can be inserted smoothly into the hole. The sleeve of the anchor should be flush with the surface of the ceiling.
Attention: Do not tighten the screw during the test, otherwise the heavy-duty anchor cannot be removed. The final assembly follows in connection with the ceiling hooks!