You can add your company unsubscribe/preference centre link into the branding templates by heading to Organization > Branding.

Under the branding colours entry, you will see the option to add a 'Company Terms & Conditions URL', then an option to add 'Company Unsubscribe/Preferences URL'. Add the URL of your unsubscribe or preferences page in the line below and you're good to go.

This will populate the email and landing page templates with extra text after the line, 'You can withdraw your consent at any time by contacting the sender of this email' (new text after this line >) 'or by visiting {Your Company Name}'s preferences page'. The page will be linked as per the below example: