We do not have a download file for the latest version (3.8.13), but you can try downloading it from the developer's site
Download version 2.5 from Mac Informer
Version: 2.5
Date update: Jul 14, 2016
File name: bitnami-joomla-2.5.6-0-osx-x86-installer.app.zip
Size: 94.6 MB