What Einstein did do for the Atomic Bomb was to co-sign Leo Szilard's letter which got the attention of President Eisenhower and kick-started the Manhattan Project.
https://en.wikipedia.org/wiki/Einstein%E2%80%93Szilard_lette...
https://en.wikipedia.org/wiki/Einstein%E2%80%93Szilard_lette...
The Advisory Committee on Uranium was the beginning of the US government's effort to develop an atomic bomb, but it did not vigorously pursue the development of a weapon.
The Frisch–Peierls memorandum and the British Maud Reports eventually prompted Roosevelt to authorize a full-scale development effort in January 1942.
https://en.wikipedia.org/wiki/Mark_Oliphant#Manhattan_Projec...