Must I make up for the food if I ate a few minutes before the Fajr athan, based on the iPad's timing, while the mosques have not yet called the athan and according to the Umm al-Qura calendar the time has not yet begun?

One must abstain from things that break the fast at the advent of the true dawn, not upon hearing the adhan (definition), based on the Almighty's saying: "And eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]. Then complete the fast until nightfall." So, if the eating occurred before the advent of dawn or before the adhan of trustworthy mosques, then the fast is valid.