Tokomak energy also made a YouTube video to walk you through the paper:

https://www.youtube.com/watch?v=hWW9kE2lUqo

This is a previous paper that has garnered a lot of downloads:

On the power and size of tokamak fusion pilot plants and reactors

http://iopscience.iop.org/article/10.1088/0029-5515/55/3/033...