UB version should work fine on G4 and G5 machines. It is possible that the G5 with OS 10.3.9 may require an update to 10.4.x
You can download and install the latest version and then uninstall and install the version 1.2.x in case of troubles. I recommend to use the latest version if possible to reduce compatibility problems in the future.
Regards,
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Mateusz Wozniak
PSPaudioware.com