Step 4 means that inside your game folder, you should have a folder named "Content" and a application named "Celeste.exe"
If you have this, then your folder structure is correct.
For the other part of your problem i am to no help, sorry.
Edit: Found this by looking around https://itch.io/t/828532/cant-lauch
"if u look it seems like it cant find a monocle or something, i had 3 different folders with celeste stuff in each, stuff like the application, error log and whatever fmod is in one, then i had two different files called backups and content. because it said file not found i tried making its job easier and basically just chucked all the Celeste stuff on my computer in one folder and it works fine, the application opens and it had my previous save.
i dont know if what i did actually fixed it or if it just fixed itself, but it worked for me."
REALLY DUMB SUGGESTION: Try downloading the game again, unpack it - > try it, if it doesnt work download a new copy of the game and unpack that one aswell. Now cop all the files you unpacked the second time into the folder with the game that doesn't work, pray.
I honestly don't think this will work, but it's worth a shot.