if they signed up for a new account using the link you sent then it will automatically be linked to your account. you can check the status here.
https://squareup.com/dashboard/account/referrals
when you have free processing enabled, Square will take the fee on each transaction like usual. Then, when your deposit gets sent to your bank, Square reimburses the fees. If you take a look at your Deposit Report, you will see that the fees have been added back to your deposit.
