On some computer systems the installer might stay in 0% or 80% for a very long time. this can be caused by a slow computer, a slow hard disk or a slow internet connection. This client is big and requires at least 2GB of free space to install. If your hard disk is slow or your computer is slow or has little memory, the installation will take longer.
Also there is a dependency for this game called Net Framework. Most computers have it already, but if yours does not, your installer might have a window asking you to approve the installation of Net framework in a location which you cannot see.
Please give it time. The installer will most likely continue or report an error if it encounters one. If it reports corruption, try downloading the client again, make sure the file size is larger then 700MBs at your end.