I found the following: https://www.adobe.com/support/documentation/en/flash/cs3pro/Flash_CS3_Professional.pdf
Note that Flash CS3 is very old and not supported on any modern operating system. See Flash CS3 System requirements at
Also, moving this topic to Adobe Animate CC forum (Flash Authoring is now Animate CC)
unless you use an old mac os or windows you'll almost certainly have significant problems.
with mac this may help, https://helpx.adobe.com/creative-cloud/kb/install-creative-suite-mac-os-sierra.html
to download the trial:
note: newer os'es (especially mac os'es) are not compatible with older programs (especially adobe's). this may help you start your installation, https://helpx.adobe.com/x-productkb/global/macos-high-sierra-compatibility.html that said, you can download the installation files using the below link.
Single user licensee downloadable installation files available:
And a big thank you to Jim @ Prodesigntools for helping me with these links!
Free trials were to try before buying. You can’t buy CS3. So don’t expect a free trial.