It is a copy of a Catalan series called "Polseres Vermelles."
Throughout the series, several characters can be seen wearing "vintage" tee shirts with US states, cities, and attractions on them.
While the first two seasons of the Italian series closely follow the original Catalan series Les bracelets rouges (2011), the third season is original. That is because the Catalan series didn't continue after the second season.