Final answer:
Oklahoma's initial requirement to become a state was to adopt a constitution that met federal guidelines and then apply for statehood, which Congress had to approve.
Step-by-step explanation:
The initial requirement for Oklahoma to become a state, based on historical precedents set out by the Northwest Ordinance of 1787, was for the territory to adopt a constitution that upheld certain standards, such as forbidding slavery and protecting religious freedom, and then apply for statehood. This process of state formation included developing a state government that would function in harmony with federal guidelines.