I downloaded the installation dmg I accessed this and read the relevant files noting that it said that OSX from 10.4 onwards supported and intell or Power PC supported I am using 10.5.8 Leopard. with a power book G4 1.5 GHz, 2GB DDR Sdram ATI Mobility Radeon 9700: Chipset Model:ATY,RV360M11 Resolution: 1280 x 854 Depth 32-Bit Color. Which part of the architecture is not supported?
My guess is you downloaded the LibreOffice DMG for the Intel platform and not the PPC platform. Please go back to the download page and try again. Having said that I don't have a PPC architecture so can not test the current PPC DMG file to see whether it installs correctly.
No reply from original poster nearly a month after the first report so am closing this.