It is critical to avoid unofficial "mirror" sites which may package plugins with malware. The developer has officially archived legacy versions for users of older software. LibFredo6 - SketchUcation
: "Check for Updates" is disabled in this version to prevent it from trying to update to a version incompatible with your old SketchUp software. Libfredo6 Old Version
If you have a model saved from 2016, opening it with the new LibFredo6 often results in broken bevels. Loading the old LibFredo6 restores them perfectly. It is critical to avoid unofficial "mirror" sites