Hmm… could it be windows there were updating in the background? I’ve had an incident, where windows update was updating in the background, and got a message as you did when I wanted to run another installer.
But wait some seconds and press continue / try again - if possible. Otherwise check your task manager (ctrl+alt+delete) in windows, to see if more instances of Steinberg installers are running in the backgound. Then make sure, that no steiny installer or steiny synth was running in the background, when you started the content installer.
SLL