I have the same problem. Login just refuses to work no matter what I do. I have added the path to enviromental variables and everything. Also tried to open butler through the directory, but I get the system cannot find file specified when I try. Some help with be appriciated.
I believed it was something about me not getting the right URL, it keeps putting the user in front like C://name/butler
He showed me that you can click where that arrow points and it will be able to be edited, delete it, and put cmd, which on Windows will open the command panel on that folder
And then I needed to configure the Butler file using this to open the Butler.exe from the folder 
, and then type something like butler login
This may not work. but it worked for me