You will need Deltapatcher to install this mod, like any other mod.

Also, since DELTARUNE™ uses game_change, each chapter is technically its own game. Hence why everything there are five files here.
This means that you will need to patch each chapter individually, not much I can do about that.
(By the way, if you can find something that can do this in batch, it'd make my life ten times easier)

... Enjoy my Ralsei mod!