To display screensaver as Logon screen saver, i.e. when no users are logged in, please follow the instructions below:
Ultra Screen Saver Maker
For example, to display screensaver c:\Windows\SysWOW64\test.scr after 60 seconds when no users are logged in, set the following registry keys using Command Prompt as Administrator:
reg add "HKU\.Default\Control Panel\Desktop" /v ScreenSaveTimeOut /t REG_SZ /d 60 /f
reg add "HKU\.Default\Control Panel\Desktop" /v ScreenSaveActive /t REG_SZ /d 1 /f
reg add "HKU\.Default\Control Panel\Desktop" /v SCRNSAVE.EXE /t REG_SZ /d "c:\Windows\SysWOW64\test.scr" /f
Warning: Be very careful when modifying the registry!
See more information how to change the logon screen saver in Windows.
Live Screensaver Creator
Unfortunately, it is not possible to display Web based screen saver as Logon screen saver. It is run by the LocalService account that has minimum privileges on the local computer and presents anonymous credentials on the network. Creating both Edge WebView2 Control and IE WebBrowser Control from Microsoft simply do not work in such environment.