Hi Marc, and welcome 🙂
You can create and configure Divi Areas on the wp-admin panel at "wp-admin > Divimode > Add Divi Area", or "Divi Areas"
On that page you find a new meta box that contains all Divi Area options (Triggers, Behavior, Layout).
Tip: Use the "Detach" button in the top/right corner of the metabox to move it freely on the screen while you edit your Popup contents.
Let me know if you have any other questions. And have a great weekend!