Download v6.2.1 from here: WICED Studio Wi-Fi/Combo Docs & Downloads
Unzip BOTH files to a folder right off the C: drive, something simple with no spaces in it like \wiced
Double click the installer.
If you download the double click the exe inside the .zip the install will show the same symptoms you describe. The files must first be save and reside in the same folder as one another when you execute.
If this continues to give you problems, post the install log from the %tmp%\wiced_install_log folder here and the applications team will take a look.