If you know where you installed it then you should find a file called 'version.h'. The contents of this text file tells you what version you have got. Project Designer uses this to detect you have entered the correct folder name.
So make sure that in the Generate window you enter the complete path name to where the version.h is stored.
By 'complete' I mean start from the beginning ie the drive letter. So don't use a relative path like '../../blah/thing' but DO use an absolute path like 'C:/mystuff/blah/thing'.