We were 3 persons visiting Lisboa and staying in Dora's appartment, and we had a hell of a time.
The accomodation is slightly away from the city center (45/50min walking), but 10min by uber (5 to 8e) or 15-20 by bus so not a big problem.
The appartment can house up to 6 persons, so at 3 we were fine, but it might be getting cramped by more than 4, actually.
Dora was the perfect host, welcoming, available, with good advice, would recommand staying there without any doubt !