Here's what worked for me because I was also having difficulty (on steamdeck):
Uninstall the game in steam
Delete the "Star Knightess Aura" folder from "/Home/.steam/steam/steamapps/common"
Install the game again in steam (So you have a completely fresh correct folder structure)
Unzip the patch into a test folder (e.g. /Home/Downloads/test) AND MAKE SURE YOU SELECT "PRESERVE PATHS WHEN EXTRACTING", do not click "Extraction into subfolder:"
Double check the folder structure is correct:
When you know the structure is correct, then copy the "mods" folder you just unzipped in the test folder into /Home/.steam/steam/steamapps/common/Star Knightess Aura/
Click "Write into" when copying
If it worked Aura will be naked on the menu screen.
(Thanks for your hard work aura-dev)