Upload workouts .zwo

I write here because I couldn’t upload a workout (a file with .zwo extension).
I previously read that you have to open the folder Downloads (the path has to be …/Zwift/Downloads/userID but i only could find the downloads folder inside the “assets” and the “data” folder finding that there is no userID in that folder .
Ignoring these facts I copied the zwo file inside the download folder but i don’t find the custom workout on zwift.
Can you explain what can I do .
thank you very much