UBER is indeed available in Buenos Aires although there is much controversy over it, as there has been around the world.
But, since September 2020, it was declared Legal.
In Buenos Aires, the company offers its services to all who download the application. Users can pay with a foreign credit card or in cash with Argentine pesos.
Depending on the route you want to take, it may be convenient for you to take public transportation, which is obviously more economical and often has exclusive lanes to travel through heavily congested areas. Sometimes it turns out to be more practical and faster.
Also, there are other options like using the CABIFY app that works as well as UBER. It is a bit more expensive, but 100% legal. Another option is Didi, fairly new.