Hi, yes v18.104.22.168 ( max6 and max7 versions of CC ) is compatible with 3ds max8 as well. Please re-download the file, it may be corrupted during download. When you run the installer it should present you some information and ask you the location of your 3dsmax, it is not an silent installer.
Also please note that the installer exe is acually a self extracing WinRar archive. you can open it with RAR if you prefer.