PlaceMaker works for both Windows and Mac.
Since PlaceMaker imports data from a variety of online sources, an internet connection is required to use PlaceMaker.
If your system can run SketchUp, you should have no problem running PlaceMaker. However, the import process will be faster with a fast internet connection and more powerful CPU.
It is also recommended (but not required) to have at least 8 GB of RAM.