What you are referring to as an error is actually a linter caution, not an error. We are following instructions. As I recall, this is the only lesson that expects the universal selector, and perhaps might have explained better what the downside of it is. Something to read up on, for your own knowledge.
I am in the exact same situation. It won’t let me move on stating “Oops, try again. Make sure that you use the universal selector * to give a border 1px wide.” while my CSS is *{
border:1px dashed #3A5FCD;
}