Please follow the steps below to see how a customer would get Referral link when he becomes a member of the store or by signing into your store with his existing account credentials.
Open your store front in a private / incognito window (so that you can browse like a customer)
You should be able to view the "Refer and Earn" icon on your store (provided you have enabled the referral program)
3. Now click on "Refer & Earn" and you should view a widget with option to either join as a member of your store or to sign in to the store with existing credential.
4. Once you have logged into the store you should be able to view the referral link generated automatically which can be used to refer your friend and earn the reward.
5. Now open a new private / incognito window and paste the link and click enter (so that you can browse like a friend)
6. Now you will be instructed to provide your email id to receive the coupon code. Once you provide the email id the coupon code would be emailed to the provided email id and it would also be displayed at the store frontend.