What does the Allow Default Form Setting do?

If the Allow Default Form setting is enabled then the default Spotlight and/or Pop Up Subscribe form(s) you've designated in your Subscribe Global Settings will show in addition to any Manual Placement form(s) that you have embedded on a page.

The Allow Default Form setting is only available on the Manual Placement form type. 

If enabled, then two (or more) Subscribe forms will show on the page. You'll only want to enable this setting if there are multiple Subscribe forms being placed on a page.

How to Enable

Navigate to Grow Publisher Portal > Subscribe > Forms. Click Manage Form on a Manual Placement form and scroll down to expand the Advanced section. Then toggle on the Allow Default Form setting if you want to have your default Spotlight and/or Pop Up Subscribe form(s) display on the same page as the Manual Placement form: