The article explains it- they formed a company, sold shares to residents, built the network, and then leased the network to an ISP. They then buy their service from the ISP.

I am very interested in similar projects, like B4RN in the UK- I am working to form a similar community initiative in Dade County, MO, USA. (DadeCountyFiber.org). My current plan is to operate the ISP locally as a nonprofit, rather than leasing it to the ISP as in the article (More like the B4RN project).