Salvatore gave us a few tips about the location and what is around. There is Eurospin and Super Elite supermarket near. The metro is a 4-min walk away and a few buses very close too. The apartment is rather large, there are 3 A/C units, 2 bedrooms (1 with a double bed and the other one with 2 single beds) and a balcony.
There is an ATM (Bancomat) on Via Cesare Baronio 12, you can get to it even after it closes, you just have to slide your card in to the reader that is to the right of the door. They do not charge for the withdrawal themselves but your bank can charge you a fee for withdrawing abroad. Also make sure to deny/decline the conversion/DCC so you get charged in the local currency.
If you arrive at the Ciampino airport, just before the exit door there is a red sign saying something like a BUS for 1.5€, go there and you can buy a single-fare/100-min ticket for 1.5€, 1-day "BIG" ticket for 6€, 3-day "BTI" ticket for 16.5€ or a 7-day "CIS" week pass for 24€. They are all valid for the 520 BUS (just search the route on Google Maps, it will show you where the bus stop is) that can take you to Cinecittà metro stop and there ride towards Battistini to Furio Camilo. Also make sure to validate the ticket on the bus (there is a yellow box in the bus into which you put the ticket with the arrow facing down).
This ticket is valid for all the public transport in Rome and also for the train that can take you from Roma Porta S. Paolo to Ostia Lido Centro to the beach (Google Maps for some reason does not show this train but during the day it runs every 15 minutes from platform 2). From Lido Centro you can walk towards the Lm Toscanelli/Magellano bus stop and there you will see a section of a public beach.