3 friends (24 years) looking for an apartment in Lisbon

We are 3 medical students from Croatia traveling to Lisbon in the summer of 2018 for 2 months via Erasmus+ programme. We are searching for an apartment in the city centre or near the centre so we can easily go to the hospitals where we will work during our stay. We would like for the apartment to have 2 or 3 bedrooms (3 beds or 1 double and 1 single bed), an equipped kitchen, bathroom and a washing machine. It would be ideal if the bills would be included in the monthly price.