I'm not getting that error when I check your campaigns and click the View as Webpage link in Previews nor Test Sends.
Are you getting the same error when you click it on other devices, or off-network? Does the error screen show in other browsers, or in incognito/private mode? Are you running any ad/pop-up blockers, VPNs, browser extensions, or security programs you can temporarily disable, to see if that will allow the webpage to load?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ William A Community & Social Media Support