mac mini 2.26 GHz intel core duo late 2009 with 10.9.5
Hello,
as per system requirement document you should be fine with 6.2.8 from Download LibreOffice | LibreOffice - Free Office Suite - Based on OpenOffice - Compatible with Microsoft for macOS 10.9 (Mountain Lion)
Note: This answer ignores your tag macos10.8 and regards title and details only, which mention 10.9.
Hope that helps.