There is absolutely no way that you will be as productive as an already experienced developer in two weeks with the Erlang/BEAM/OTP/Elixir stack. It's a completely different world compared to what you are used to, and that's probably a good thing but the time to adapt and become really comfortable is going to be at a minimum closer to a year than a couple of days to weeks.

People who are already familiar with the actor model, soft real time systems, supervision trees and possibly PROLOG would likely move faster.