I'm getting an "Account for the User not Found" error when trying to run the script at MCC level.
This happens because you are either running an MCC script code in a child account, or you are running the Account script code in an MCC account. You can make sure to get the correct one when downloading the script, as there are two options available: For Single Account and For MCC Account.
If you downloaded a Single Account script code, the script will display the error in the logs each time it runs.