If the client does not receive the email, try resending the Invite while on the phone or messaging with them.
1) Have them check Spam or Junk Mail.
2) Have them search for your name and downpayment.gift in the inbox.
3) Test send to them from your email. Is there email working elsewhere?
3) If they still can't receive the email, contact Support.
Have their mobile number ready. We can SMS the unique sign in link to them to get onboard.