Thank you for your post!
Saving Self Contained Copy: "Create a copy of the current file with all container data that is stored externally (both open and secure storage) embedded in the file’s container fields". The copy of current file and compacted copy options do not copy externally stored data. The authentication is most likely to ensure secure (potentially significant external data) isn't just bundled into a standalone file to be more easily distributed -I will try to get a definite answer on this though. For more information you may also see Saving and copying FileMaker Pro files.
I am also going to move this thread from the FileMaker Community Feedback Space, which is specifically for input on the Community itself, to the Discussions Space where you should receive even more views and potentially more advice!
TSPigeon, Thanks, and thanks for moving the threads to the correct Space. It appears that the login is required to effect embedding in the solution's container field. Otherwise the file is created but is just a copy of the original, containers not embedded.