This is the 5266th most frequent Russian word.
обычным
"Ordinary" or "usual."
The word 'обычным' (declined form of 'обычный') is used here to describe the cafe as not special or extraordinary, but normal or average.
Мы встретились в обычном кафе.
We met in an ordinary cafe.
The word 'обычным' describes the route as the one that is typically or usually taken.
Он пошёл на работу обычным маршрутом.
He went to work using the usual route.
Here 'обычным' refers to the perception of the situation as being normal or not out of the ordinary.