Its not a countdown but the actual time. Its used for the conductor to make sure you are showing the ticket on the app and not a screenshot of it.

Oh totally missed that with countdown. So screenshot is not allowed?? All the YouTube videos mentioned to have the screenshot ready in case the app don’t connect or bad networks 

No, cause like that you could share the screenshot and multiple people could use it. Its still a good idea to take a screenshot in case the app strikes. But you dont need it for case of bad network. the app works offline. But, you need internet to activate your travel day anyway before travel (that generates the ticket).