I get up to the very last part where I circled it in red.
I get that it's $$1 - P(\text{exactly 0 person over 6ft2in}) - P(\text{exactly 1 person over 6ft2in}) = P(\text{at least 2})$$
What I don't understand is why they are equal to $e^{-μ} + e^{-μ} μ$
Where did $e^{-μ}$ even come from?