The Last to Libre script only supports Python 2, this isn't clear in the instructions
Just a heads up, the Python scripts only support Python 2. A notice on the wiki page would be helpful.
Also, make sure to run C:\Python27\python.exe rather than simply python.exe, if you already have Python3 installed to the PATH. I simply opened a command prompt in my Download folder and ran
C:\Python27\python.exe lastexport.py -u Dark_Ronius
(my username... replace this with your own ;) )