Anything from that site is likely old and not packaged correctly.
You can simply use the Attribute Inspector plugin to view the “GeoReference” attribute dictionary.
[url]Page Not Found | SketchUp Extension Warehouse
You can use Ruby to retrieve the values from the dictionary.
x = Sketchup.active_model.get_attribute("GeoReference","ModelTranslationX")
or
dict = Sketchup.active_model.attribute_dictionaries["GeoReference"]
unless dict.nil?
dict.each {|k,v| puts "#{k} = #{v}" }
end