When installing Syncthing for the first time, did you use the installer from https://github.com/Bill-Stewart/SyncthingWindowsSetup? If yes, then you should refer to their readme instead of the official Docs. The procedure you linked above applies to a situation when you download the bare syncthing.exe binary and want it to start automatically.
OK, I see, thanks for your help. Yes I installed from Github. I now see there are 2 docs online and that’s a bit confusing but I simply re-run the install and checked the autorun and everything is now fine.
May I ask you again: - What is the difference between syncthing.exe and “start syncthing”, “stop syncthing” found in start menu?