There is the current stable version 18.104.22.168 available from the regular download page, and a new beta version. In a few days we are going to roll out the final 6.9 release and this new version will replace version 6.8.
Unfortunately, we do not provide earlier versions. We always recommend that you use the latest version, on both sides (Viewer and Host). Otherwise, we cannot guarantee that the bug you may encounter is something new and not just a known bug that is already fixed in a subsequent update.