The building is from the 1940s.
But this is a pretty common setup for condos in Swedish cities. Rentals usually have access to the same infrastructure but at higher prices due to kickbacks demanded by the landlords from the ISPs.
The backbone of it all is a state owned fiber connecting the cities together with municipal fiber.
But even outside of the cities FTTP is quite common. There are companies which specialize in finding rural areas where there’s enough interest to justify the cost of connecting them and then coordinating getting an economic association setup to own and manage the local infrastructure.