ADBESTDSCS3_ESD1_WWE.exe for CS3 - LOCKED, CS3 is dead

The CS3 activation server has been removed, so the product may not be activated even if you have an installer

That file is just an extraction file. If you have the extracted files/folders that it produces, then that's all you need. The setup.exe file to install CS3 should be in a folder called AdobeCS3 along with all the files and folders needed. If you have a copy of that and your registration code, you should be good. Otherwise you'll have to try contacting Adobe support if they no longer have the files on their site.

You needed to keep it. It’s gone. Maybe you have a backup?