Why does Debian install tutorial put files under catkin_ws?

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ROS installed perfectly on my Ubuntu laptop but when I attempted to do a full install on my Beaglebone Black's 16 Gig micro SD, the bulk of the files are in the wrong place! Most install under the home/user/catkin_ws directory, while on Ubuntu they installed under /opt/ros/hydro directory. On the BBB there wasn't even an /opt/ros directory created! It was when I got to the tutorial step to run roscore that things broke. It said, Please run 'rosmake rosout' But that command wouldn't work either. Catkin_make returned an error regarding the multitudes of files it found in its directories! Actual output below: