You can publish subscription centers as a native marketing page running on a Dynamics 365 portal, or set up a marketing form that's embedded on an external site. You can use either of these types of pages as your primary subscription center if you prefer not to use the default one. When going with this method, you will not need to create a Subscription List nor subscription form as these should be part of your external site.
- Create a new Content Settings
- Fill out the required info, then go to Subscription Center.
- Type in the exact URL of the External site you wish to use including the https://