Hi Duc,
the error message "Course could not connect to the LMS" is connected with the SCORM tracking (contrib-spoor) extension. This is in fact working as intended but slightly annoying while you are authoring.
Please uninstall contrib-spoor to remove these error messages. You can run this via the command line with the following command:
adapt uninstall contrib-spoor
Hope this helps.
Thanks,
Sven