I'm in the process of testing out SmartStore, and may I say what a high quality project!
Unfortunately however I'm having issues installing the latest Authorize.net plugin. It seemed to upload fine but when I execute the install task it quickly errors out (see attachment)
Value cannot be null.
Parameter name: key.
I am a poor man's developer and am running the SmartStoreNET solution with visual studio in debug mode, if that helps.
I tried to add the authorize.net project as downloaded from git but had several issues trying to build the solution so I just removed it for now.
Any help would be much appreciated.