The decrease in total primary energy supply required due to electrification, even as there are more total users, is a bit strange.
This report suggests that it is because renewables are fundamentally more efficient than fossil-fuels (both for electricity generation and locomotion) but I don't think that's the entire story.
I think they are counting the energy input into a system strangely. For fossil fuels, they use the inherent energy of combustion of the fuel, even though power plants are only about 40% efficient.
For photovoltaic solar they count the energy out of the solar panel, not the radiant energy received from the sun. This means solar panels appear to be "100% efficient" even though in truth they are only about 25% efficient.
I suppose their argument is that the light would have hit the earth anyway.