What was requested of the Kirtland AFB by the Manhattan Engineering District?

the answer is: Developed the Armed Forces Special Weapons Project at Sandia Base to coordinate military nuclear activities.

In its earliest development, the Kirtland AFB was established only to create existing runways and hangars for military use. Overtime, the Kirtland AFB developed into united states Air Force Global Strike Command and sixth largest in the Air Force in the country.

Due to their remote location, they were chosen by Manhattan engineering district to develop the nuclear weapons because they have more room to test out their new weapons compared to air base on other states.