When trying to install using the install from zip archive, this only works if the runtime folder in the zip file is a top level file. If for instance there is a folder in the zip file that contains the runtime file then it doesn't work. Then the only way is to manually unzip the file then merge it with the runtime you want to contain it. How you do this differs I believe between windows and Mac. In windows you can drag and drop, but I've never used a Mac, however I assume there is a way of merging folders rather than the new one replacing the old.