you need to create the opt out as in tracker sub panel on the Campaigns detail view,
when done go into the email marketing Edit View which has you email template, then editing the email from within there it shows the ‘Insert Tracker URL:’ function where you just select the opt out tracker you created and add it where appropriate
I did create the opt-out in the tracker subpanel, however I totally missed the Edit view in the marketing campaign is different than the “standard” edit view in Email templates… Thank you, now my opt-out link works perfectly!