When I install this, and try to authenticate, I keep getting a 500 error when it returns me to my site. I have installed and reinstalled the add-on several times.
I noticed in the return URL, the action 'a' parameter doesn't have a value - is this correct? eg
http://www.mysite.com/manager/index.php?a&token=1%2FXe3gvL5eLvnD3CewjQojs-jDOdFjBnwgCv3UU2fgMCo
I didn't notice anywhere in the package installation instructions that you should fill in some system settings before attempting to run the extra. It would seem an obvious idea to add this line in the installation instructions for clarity.
It would also be nice if there were clearer instructions for specifically which details are needed for the system settings!