(This is probably explained in the article, but I don’t have a subscription.) The National Ignition Facility (NIF) creates fusion by bombarding a fuel capsule with lasers. The laser beams are reflected many times to build up energy, and to converge on the capsule. There is energy loss during that process so the laser energy that goes into the capsule is a small fraction of the electricity used to fire the lasers. When they say they got twice the energy out, that’s compared to the laser energy going into the capsule, not the energy required to fire the lasers. So its a long way off from a practical power plant, but still important progress.

The purpose of the NIF is to study what goes on inside the capsule - for better understanding, and to figure out how to get the most possibly energy out of a fusion reaction. Once they have figured that out a possible next step is to design a system that delivers laser beams with less input energy. It’s easier to do that after you know the ideal way for beams to interact with the capsule. Or maybe we never build a power plant based on the NIF design, but the findings help to make other reactor designs work.