Forgot to add a course on my application, what can I do?

I am going through community college and I recently found out that I forgot to include a nontransferable course which was worth 1 credit (I got a B). It was taken during my High School year so I completely forgot to add it. I recently sent an email to the UC application docs@applyucsupport.net and their response was “We received your document and it will be view able to the Universiti(es) that you applied within 72hrs.”
Does this mean I am safe? (Also, I was accepted into a TAG so would this deny it due to the missing class in the application? Just to clarify, the class was included in the TAG but not on the actual UC application) What do they mean by “document?” I am stressing about this a lot. What should I do?