It is clearly mentioned on the pack of most hair removal
creams that they are not meant to be applied on the genital area. Anyway since you have already done that, what you are experiencing is pretty normal. Your labia is inflammed due to the use of the cream and so you have burning sensation. It should subside on its own in a couple of days. In the meantime, make sure you maintain adequate hygiene and apply some ice if you feel more burning sensation. Drink lot of fluids.
Hope you get well soon.