You must be an American Citizen of Hispanic descent and you must speak Spanish like a native.
The only medical school where you could study in Cuba is the recently created ELAM ( Escuela Latinoamericana de Medicina). Its Mission? -indoctrination and propaganda. The school was created to "provide the opportunity of a medical education to those students coming from Latin American who have been unable to reach their dream of becoming doctors because of the long term imperialist exploitation...blah, blah, blah"
The students usually study there for free, thru treaties with their governments at home and the cuban government which in return gets to have some hemispheric influence and to promote "good will".
Medical education has suffered in Cuba terribly in the last decades. There are no resources, no access to the latest technology, and most students are failing their native countries examinations when they get back home. The result?- They are not being allowed to practice. Students are being taught by videos and proctored by senior students, which has generated a lot of protests and controversy...but you get what you get for free........SO...
I am curious to see where your idea to go to Cuba to study medicine came from.