Thanks, everybody, for your help! I found an easy workaround so that even instructors can create the symbolic link to the Student Orientation if that link is missing.
(1) Under WeBWorK 2.19, I added a new course based on modelCourse. In that course, using the File Manager, I selected the link Student_Orientation@ and clicked "Make Archive". I then downloaded the resulting zip-file (which I renamed to "Student_Orientation-symlink.zip"). This zip-file contains the original link Student_Orientation@ together with its Unix file permissions.
(2) Uploading this zip-file into a WeBWorK course that is missing the link Student_Orientation@ creates this missing link. Once this is done, it is possible to Import (using the Sets Manager) the file "Student_Orientation/setStudent_Orientation.def".
(1) Under WeBWorK 2.19, I added a new course based on modelCourse. In that course, using the File Manager, I selected the link Student_Orientation@ and clicked "Make Archive". I then downloaded the resulting zip-file (which I renamed to "Student_Orientation-symlink.zip"). This zip-file contains the original link Student_Orientation@ together with its Unix file permissions.
(2) Uploading this zip-file into a WeBWorK course that is missing the link Student_Orientation@ creates this missing link. Once this is done, it is possible to Import (using the Sets Manager) the file "Student_Orientation/setStudent_Orientation.def".
Thanks again for your help!