The "files are corrupted..." error is typically caused by the security software. The file downloads fine, the security software then quarantines files when your run setup.exe which makes the download "corrupt".
The typical solutions are:
- set an exclusion for the gcd file and/or the directory you unzip to
- temporarily disable your security software to install the program
- reboot in "safe mode with networking", install the program, reboot normally
The workaround you'll need to use depends on your security program. Also, to prevent any confusion, the giveaway for Phototheca has expired so you won't be able to install it.