Hello @Boris24,
The text you quote says that "[name removed] signed up, but hasn’t taken a trip yet."
This would indicate that he has to make a reservation on Aribnb and travel himself, before you will be given the credit.
I don't know if you intended the credit to be for when he travels or when he hosts.
Either way, the trip he books or the trip booked with him has to be a qualifying one, over a certain monetary value etc. as outlined in the article below.
how-do-i-earn-travel-credit-from-referring-a-friend-to-airbnb
If that article doesn't expalin your problem then check the "Community Help Guides" article that you'll find when clicking on the "Get support" link when you're on the "Ask the Community" page.
Steve.