System Pages
System page settings apply to Hubspot accounts with the following plans only: Marketing Hub Professional, Marketing Hub Enterprise, CMS Hub Starter, CMS Hub Professional, CMS Hub Enterprise, and Legacy Marketing Hub Basic. Systems templates are used for certain types of pages generated automatically by HubSpot.
Currently, HubSpot doesn't support drag-and-drop customization for the system pages. Any customization for system page templates included in the theme would need to be done by a developer.
Subscription Templates