Usually it is safe to use the latest SVN code but at times there may be some features that are not complete so download and use at your own risk.
1. download tortoisesvn or another svn client
2. If using tortoise (not sure about other clients) right click on a folder where you want to download pligg and go to tortoisesvn > export
3. use this url if you're not using command line
https://pligg.svn.sourceforge.net/sv...g/branches/9.x
that will get you the latest up-to-the-minute code.