The other answers are correct to follow the installation guide. These APs are heavier (2.4 pounds or 1.1 kg) because it's not a client device, but an infrastructure device, and the heavier weight is simply an indication of a good ruggedized product design with appropriate IP67 sealing and thermal characteristics. The weight is not an issue when properly installed as per the install guide.
If you're finding that you must install on ceiling tiles (which can typically support more than twice that weight without concern, but still) you must check the tile manufacturer's specs. Most/all ceiling tile manufacturers have guidelines for maximum weight/loading, as well as accessories for suspending heavier objects such as signs. But it depends on the type of grid layout, the spacing of the suspension points, size of the tiles, etc to determine the safe weight and spacing limits of signs, lighting, and APs for example.
You should also be able to use any open hole in the mounting cradle, or the grounding strap screw if you're not using it, to attach a lightweight safety cable that connects to some other solid mounting surface above the ceiling for example, so if the actual mounting mechanism or ceiling tile ever failed (like from water damage or whatever) the AP would be caught by the safety cable instead of dangling by the Ethernet cable or falling to the floor.