Hello Albert and All,
For the new error message of "may be opened in another instance of the application", please close all the project files and delete *.lock file if you could find it the same location of the project file.
For "access" issue, I suppose you are not admin or you could not modify the model in "program files" folder, so please copy the model to a local position.
HDLI
You are navigating away from the AIS Discovery experience