It looks as if Sketchup Make, the free, offline version, is still available (https://www.sketchup.com/download/make ), possibly just harder to find now they push Sketchup online. But if not, you should be able to find oder releases by searching online - at least they used to have a repository of legacy versions. As for online conversion - not as far as I know. Maybe you can publish to the warehouse, and select a kmz/dae download of your own file... ok