It means a place where everyone has previously decided to meet or gather : The assemblage point for our departure is the lobby of the Waldorf Hotel. The assembledge point for the attack will be the port on the east side of the island.

It's actually the "assembly point" if it means what I expect. As the other commentator said, it means the point at which people gather. Example: "The assembly point for the trip is in front of the museum at 3:00pm."