@Youngin Kim,
The error message you provided is not for running the simulation file -- this is when you are opening the FDTD CAD/GUI. The command "fdtd-solutions" is what you run for the CAD/GUI.
How do you run the simulation file? Are you running from the CAD/GUI or from the command prompt/terminal and what command do you run to run the "simulation.fsp" file?
Send a screenshot of your desktop opening and before running your simulation and screenshot of the error message - where you cannot run the "simulation.fsp" file.
You are navigating away from the AIS Discovery experience