Unable to set up Arduino web editor in Windows 10

Here is the URL the "DOWNLOAD FOR WIN64" button points to:

https://downloads.arduino.cc/CreateAgent/Stable/ArduinoCreateAgent-1.2.4-windows-amd64-installer-chrome.exe

Try opening that link to download and then running the downloaded "ArduinoCreateAgent-1.2.4-windows-amd64-installer-chrome.exe" file to install Arduino Create Agent.

Once Arduino Create Agent is installed and running, you can jump straight to using Arduino Web Editor. No additional setup is needed.