Also, don't misunderstand me, in that 1500kcal daily intake, you must include a healthy, clean diet with a minimum of 80g of protein a day. There is no "I will eat three cakes a day and be around 1500". With that, if you can maintain such a diet at only 1500, you'll become only skinny fat, and sick.
What is your basal metabolism rate, and how much do you run?
There is no point to be so restrictive. It's not all black and white as the app says. The best will be to stick to 1500 calories a day for a week and see where will it get you. On the days you run you can eat more, but it depends on do you run to lose weight or to maintain a healthy cardiovascular system? If you run only because you want to lose, then there is no point in eating more than 1500kcal that day.