"Moment" is basically interchangeable with "minute" for the purposes of this idiom. There are also two distinct things this could mean, and i'm not sure which it is in Spanish. Is it, "Please wait a minute, and then I'll get to you" or "May I please have a minute of your time?"
The first and most likely reason is that "Hola" does not translate to "hey". The second reason is probably that is sounds weird since, "Hello, one minute please." is most likely said in a formal situation. You reach the reception desk and the receptionist says, "Hello, one minute please."
While that might be used in the same context as this sentence, the sentence here does not contain the word for wait.
Wow, I think this is one of the most actually useful sentences I've ever seen from Duo.