Short answer
HubSpot's KB: subscription preferences pages are customized for each email address, so you can't generate a generic subscription preferences link. Contacts reach their own page through the footer link in a marketing email. Coded templates use the email_subscriptions HubL tag.
1. The preferences page
The preferences page template in my demo portal.

2. Subscription types
See subscription types.
3. Related
Unsubscribe links in sales emails.