Just to follow up with what Carl said, I also put together this post that walks you through the process of downloading and installing the older Flash Player from the Archive page.
Help! Is anyone else unable to install an older version of Flash on their less-then brand new computer(PowerMacG4)?? I'm running 10.5.8. I've downloaded the Uninstaller(which has a pink x in the upper-right corner) but two versions of Flash remain on my computer. When I try to install the version of Flash which adobe has recommended I get this message:
Adobe®Flash®Player cannot be installed.
Devices with PowerPC processsors are no longer
supported. Click below to download the last version
Flash Player for PowerPC.
Get Flash Player for PowerPC
I then click underlined “Get Flash…” which takes me to the same page which asks for the operating system I have and the version I need, I type in what they offer and go through the same thing again!!!