What is the best way to get to this hostel from the Lisbon airport?
You need take the subway to Restauradores station, it's on the blue line (Azul). From the airport you get on the red line (Vermelha) to Sao Sebastio. Once you're at Sao Sebastio, you take the blue line toward Santa Apolinia and get off at Restauradores. And from Restauradores, its a 10 minutes walk to the hostel.
Get an answer from Safestay Lisbon staff and past guests.