When I click next, I want to show the popup.
You have to define new event. In the form editor go to ‘Właściwości’(1) → ‘Przepływy’ (2) → ‘Akcje’ (3).
To add new event select ‘Dodaj akcję’ (4). First, you need to choose an action trigger (5) in our case it will be a Page. Select type of event (6) - going to the next page is ‘NEXT’. below (7) you can add call condition, it’s not mandatory. Then select what action you want to trigger (8) and on which component (9).