When I click “Help → Cubase Help” a dialog box appears that says “No apps are available to open this type of link (file)” and suggests I visit the Windows App Store.
What is your default windows web browser? I am guessing that windows is issuing the error as it can’t associate the link with an app.
You can assign a default web browser in Windows Settings, Apps, Default Apps…
The initial link sent by Cubase to windows to launch is probably something like You will be automatically redirected... (well it is on my system anyway) and that gets redirected to another page, maybe based on region, language etc. This works OK for me with Chrome as default browser.
You can also Choose default applications by protocol in Windows Settings so you could in theory launch a different browser to your default one specifically for https files - but probably getting a bit overly complicated…