Here is the full list of all 30 STATIONflow achievements.
Have more than 1000 passengers inside the station at once
Reach Station Rank 15
Reach Station Rank 10
Service 10,000 passengers
Reach Station Rank 6
At the end of the day, have a daily balance of more than 20,000
Reach Station Rank 3
Achieve A+ Rating with a Rank 20 or higher station
Reach Station Rank 20 on Very Hard difficulty
Achieve A+ rating with a rank 20 or higher station on Very Hard difficulty
Service 100,000 passengers
Service 1,000,000 passengers
Service 7,000,000 passengers
Service 13,900,000 passengers
Have more than 3000 passengers inside the station at once
Have more than 5000 passengers inside the station at once
Have more than 8000 passengers inside the station at once
Have 1,000,000 in funds
Have three loans at once
At the end of the day, have a daily balance of more than 50,000
At the end of the day, have a daily balance of more than 100,000
At the end of the day, have a daily balance of less than negative 50,000
At the end of the day, have a daily balance of less than negative 100,000
With no stairs constructed, achieve A+ rating with a rank 20 or higher station
With no escalators constructed, achieve A+ rating with a rank 20 or higher station
With no stairs or escalators constructed, achieve A+ rating with a rank 20 or higher station
With a total corridor area of less than 50,000, achieve A+ rating with a rank 20 or higher station
With a total corridor area greater than 100,000, achieve A+ rating with a rank 20 or higher station
Reach Station Rank 20
Reach Station Rank 50