I get the error message "opartPlannedPopupArray is not defined"
This issue occurs when the JavaScript used to display the popups is not present in the HTML code.
To resolve the problem, you must:
A) Verify that the module is correctly hooked to the "DisplayFooter" hook.
Go to the "modules / positions" menu.

Locate the "DisplayFooter" hook.

Verify that the "PlannedPopup" module is indeed present in the "DisplayFooter" hook.

If the module is not present, you must hook it to this hook. (View the official Prestashop documentation).
B) Verify that your theme uses the Footer hook.
Ask your webmaster or theme developer if the "DisplayFooter" hook is indeed used by the theme.