Did you check that the email you sent the invite to is correct? The invite email might also have ended up in their spam folder.
Please make sure to enter your client's correct phone number. This will connect them automatically to your training space when they sign up with PT Mate.
Did your client enter the correct details of your business (name, business name, your phone number)? If they did, make sure that you've entered them the same way on your end in your Account Settings.
If you made a client inactive in your list and your client connects, they won't be able to access any of your sessions. If that happens, simply make the client active again on your end.