Inside of the ZIP file that you should get with the Ko-Fi/Patreon release, there should be a folder titled "SD CARD". The contents of that folder need to be copied to the root of your SD card, so that in the result you should have the following files on your SD card:
sd:/ultimate/mods/better-sss/ui/script_patch/common/stage_select_actor3.lc
sd:/ultimate/mods/better-sss/ui/layout/patch/stage_select2/stage_select2/layout.arc
sd:/ultimate/mods/better-sss/plugin.nro
You should also have an info.toml and preview.webpin the better-sss folder, that is for ARCropolis's mod manager.