I am not sure why it happens but I can successfully land to that page: https://optics.ansys.com/hc/en-us/articles/360042192813-1D-cavity-laser-using-4-level-2-electron-material
Please note that narrow spectrum means longer pulse, which will increase the simulation time. To get accurate DFT result from the frequency domain monitor, longer simulation time is required.
The CW source cannot give you accurate DFT result, since the signal lasts.
You are navigating away from the AIS Discovery experience