If you had read the article rather than just the headline, you'd know that the tech they're talking about using is not fusion but a tool for generating beams of millimeter wave energy.

The connection to fusion is clickbait. The tool, a gyrotron, was developed by the Soviets and is a well understood way to heat up plasma.

The company in the article was spun out of MIT to create drilling rigs which would use it to vaporize rock in places where conventional drilling is too difficult, ie super deep geothermal.