The files with “HIGH” in them are of higher “resolution”, with more density. They are best used for Resin printers, even if it is possible to use them when doing FDM printing. The “LOW” files have fewer microdetails and are usually good enough for FDM printing.
This guy will need some support at the back of the helmet wings. Not much but just to get the overhangs sorted. I've already pushed the feathers to the brink of what still looks good to minimize the amount required, but any more would have messed the design up too much! If you know your printer struggles with overhangs you might also want to put some underneath the shoulder pads/pauldron/WhateverTheyAreCalled.
The author marked this model as their own original creation.