The most crappy and amateurish public transport app I've ever seen
I can't believe that a large company as OASA Telematics is actually not ashamed of offering this app: they'd rather refrain from offering an app at all, for this is not even usable, using some sort of Google information, but presented in an illegible way. It's also the same information as the Google is offering, but the Google Maps app is presenting it way better. And Google Maps is at least admitting not having all information available, suggesting there might be better public transportation options. So, delete this app right away and use Google Maps, or better yet: the Moovit app. Those are your best bets for public transportation in Greece.