Will a dropped class effect admission?

I am in a bit of a pickle, I have a class listed on my UC application as something that is in progress, but I was just on the waitlist and I assumed I would get in. Now is the last day to add and every professor I have emailed asking to add me has responded with, no. This class is a prerequisite but it’s not articulated at very many community colleges, and on assist it will say that the course must be taken at UCLA. Should I call UCLA now and let them know I couldn’t get into the class?