You will have to be specific as to which multiplier you are referring to.
For Chawon we are using the growth formula from the formula sheet because we are discounting a growing perpetuity.
For the total company valuation we are multiplying by 8 because the question specifically states that the share value is a multiple of 8 of the free cash flows (and so is effectively a PE valuation).
I do explain both of these approaches in my free lectures.