What do you mean with event?
Should this be shown when the user logs in? Or do you want a page to be open and show the popup whenever something happens?
You could add a microflow timer to your page that triggers a microflow periodically. This microflow could check if your event is reached. If so, it could show a message to the user. You may need to track if the message for a certain event has already been shown or not. If you work with multiple users, you may need to store this information for each user.
I want to show after login a pop up one week before an end date (for every user). How can I make this popup dynamically?
(7 days before: end date is in 7 days, 6 days before: end date is in 6 days…..)
How should the microflow look like?