@gkont1983
How have you tried to install Libredo6 ?
The two ways are:
Download its RBZ from the PluginStore, then use the Extension manager to Install it. After that restart SketchUp to sync everything.
Or use the SketchUcation toolset ExtensionStore dialog to find it, click to auto-install it - sidestepping the RBZ download. After that restart SketchUp to sync everything.
You need the SketchUcation toolset installed for the SCF licensing etc - especially of many of Fredo's extensions.
So I recommend you download its RBZ from the PluginStore, then use the Extension manager to Install it. After that restart SketchUp to sync everything.
After that always use the ExtensionStore dialog to install future extensions - it's vital for licensing, but it offers lots of other perks too...