Popups are managed with a reusable element named Popup Manager. This allows you to use the same popup from different pages, to edit or show data and messages.
In the Popup manager you can create your custom popup. Use statuses to refer to specific data items.

To show a popup, create a custom event in the Popup Manager workflows. Pass the data you need to the event parameters, such as the item that you need to show in the popup, or other parameters that you need:

In the Custom event, reset your popup and assign the correct status to the popup. Then just show it.

In any page, you can trigger the Popup Manager’s Custom event by using the action “Trigger a custom event from a reusable element”, and specify the parameters that you want to pass to it.

Make sure that you add the Popup Manager reusable element in all the pages that have to show a popup.