The message subject and the message text are the text that accompanies the referrer's link when they share it with friends and family. This is a great way to give the person being invited more context about your business that encourages them to click on the link that their friend shares with them.
To do this, Navigate to Step 2 inside your campaign builder. Click on the Share Settings icon on the right-hand side. Here you will be able to enter the copy you want to add.
Here is an example of what that will look like in a live campaign when a person referring shares their link with a friend on WhatsApp.