This bus is on a circular route between the school and the station, and you can freely get on or off anywhere along that route!
I recommend it; it's super convenient!
「このバスは駅と学校の間を循環してて乗り降り自由！」は英語で「This bus circles between the station and the school, and you can get on and off freely！」という表現が良いと思います。
循環するーTo circulate・To cycle・To rotate・To loop
循環バスーLoop-line bus・Loop bus・Bus on a circular route
乗り降りーBoarding and alighting・Getting on and off （Ａ bus）
アメリカ合衆国 
