I think Ank is right. The only files that you need to move (and override) are the ones inside of the “IMPORTANT” folder. Those are full copies of the files that are being replaced with the necessary changes, while the ones in “files” directly in the mod’s primary folder are only the extra changes to those files that affect or add functions (ie: not the full files needed to run the game).
I would recommend starting from a fresh vanilla Strive extraction (as some of the modded files in AricsExpansion/files aren’t ones fully replaced, so using a non-vanilla will still have errors). Delete the backups folder (again) if it’s there. Copy/paste the files in the “Important/Add to Game Folder” files into your strive.exe location, then hop in and activate the mod in the install. I’d bet that’ll fix it up for you