Presumably they’ve signed an agreement to buy the power (delivered through the grid) from the plant operator at a contracted price. The plant operator can then get finance for the work required to actually deliver on the contract.

A lot of renewable energy projects were financed through similar agreements, called PPAs.

They are just buying the power. Microsoft's goal is 24/7 matching, so every MWh of power they use is matched by a MWh of clean power (generated in that same hour) that they paid for. This is called market-based carbon accounting, as opposed to location-based accounting which considers the source of the electricity that is actually used by the company's infrastructure.

There are pros and cons of each approach, market-based is a little less intuitive but not necessarily worse, it depends on the application.

> market-based carbon accounting […] not necessarily worse

They are better for the corps communication and worse for anyone else.

Transporting electricity over distance has a non trivial cost in $ but also ressources and energy, as well as relocating an industry near a clean energy source or optimizing the production units.

Carbon-matching systems are great for entreprise wanting to claim they don’t produce carbon (24/7 carbon neutral) while they do. It does not depict the CO2E one (entreprise) did product de facto.