I am visiting Buenos Aires for the first time and am looking to stay at the Sheraton Buenos Aires. I understand it is a bit dated and undergoing renovations, but that's fine.
More importantly, I have a flight to Santiago at 0520 am from AEP.
What time do I have to check in? I have a US passport with no checked luggage.
Is it possible to find a reliable taxi through the hotel or an Uber so early in the morning?
Will immigration and security even be open at that time

?
Thanks!