For advocates there is an option to set "No reward" which comes handy if customers want to create a customised reward, like described here: https://automatewoo.com/docs/refer-a-friend/free-gift-as-referral-reward/
However there is no such option for friends and this limits abilities of the customer, e.g. the cannot provide a referral reward of discount to a certain product category.
Original ticket: 3631475-zen