It is said that the Mob helped the US during the conflict with Cuba. How did the US get in contact with the mob? Instead of arresting them? Did the Mob see an incentive to help the government?

Not sure about Cuba specifically, but in Sicily during WW2 the Allied Forces did the same thing. The essential pieces of the puzzle were aid (ie bribery) and clemency. Mafia members we already had hands on were offered better deals or even early release in exchange for cooperation, while extant mafia members were contacted through intermediaries and offered money, resources, and/or weapons for cooperation.

A lot of these mobsters were trying to diversify into legitimate businesses. Just like Reno and Las Vegas, a lot of these mobsters invested in gambling resorts in Cuba.

When communism came, not only did they have investments that wanted recouping, they had valuable contacts on the ground and firsthand knowledge of the area. So the c.i.a. and these mobsters had common interest and things they could do for one another.

As to how they got in touch? I don't think they were hard to find. Hard to prosecute maybe, but by and large they were known.

Even today there are descendants that still claim they're owed reparations from the Cuban government.