I haven't tried the ALM Robot tool, but I was looking through the User Guide. At what point in the process does this error appear? Did you get past the Validate [Configuration] portion of the Wizard?
I also came across this in the Prerequisites:
You must create a Robot domain with a RobotTemp project in the destination ALM server. This is your target database that ALM Robot uses to restore the projects in the destination ALM server.
Did you satisfy that prerequisite?