I can´t open the MultiBall_2.80.blend file (so definitly not the 2.78 file…) contained in the 2.8 source files of the course either (using blender 2.81) . Error message says that file format is not supported (???). When I open the file from the explorer (without Blender running), it will not give an error message but will just open a blank project.
However, the file from the “resources” link in your answer works fine…
Obviously one of these strange things…
