Pagebuilder and MemberPress

How do I invoke PageBuilder on a TinyMCE instance that isn’t part of a content type? MemberPress allows you to create custom additions to the Thank You page from each Membership product. It uses a TinyMCE editor instance but because this instance isn’t part of a content type, there is now way to select it in the PageBuilder. (Enabling PageBuiler for the Membership content type itself works just fine.)

https://wordpress.org/plugins/siteorigin-panels/