If he drops Windows for Linux, he might as well opt for a free writing software. I read that Manuskript has pretty much all the features of Scrivener and is somewhat similar so the learning curve should not be too steep.
Maybe best to set it up in a separate partition or PC for a trial.
See also : https://alternativeto.net/software/scrivener/?license=opensource
8GB of course, and a 256 GB SSD if my memory serves me well -_-’