@Vinay7 What @Mariam19 is looking for is not a travel credit/coupon it's a cash payout. It will be listed in your transaction history once AirBnB releases it to you.
Host referrals:
A referral credit is not issued until the host you referred has their first stay that's worth over $100 USD excluding tax, cleaning fees and service fee's, so if she's not made that on her first finished booking you do not qualify for the credit yet. If she did have a stay that qualified, you will be paid within 30 days of the end of that stay They will have 150 days to accept this kind of qualifying reservation for you to get receive credit.
Friend referrals:
A travel credit is not issued until the friend you referred has a a stay that's worth over $75 USD excluding tax and service fee's, so if she's not spent that on any of her finished bookings yet you haven't qualified yet. If she did have a stay that qualified the next reservation you make it will automatically show up on the checkout page provided your trip is also over the $75 without tax and service fee's.