To add an opt in page:

1. Hover over this section
2. Click the blue + Add Section button
3. Click on (1) OPT IN and switch to the Designed tab, if you can't see it, scroll down on the left side menu using the arrow at the bottom left to find it
4. Select the template required
5. Click Save Section (top right corner)
6. Delete this section
7. Edit opt in page as normal