How do I automate coupon after customers subscribe to SMS marketing?

[luciotti]

I just subscribed to Square Marketing. I tested the email and SMS to initiate subscription. However I do not understand how to automate the coupon I want to give customers to thank them for subscribing to SMS. I tested this with my phone number but I do not understand how to automate this if I have 1000 customers agreeing to SMS. I then unsubscribed and re-subscribed to re-send the SMS with coupon but the system did not put me back in the subscribers group. So I cannot test anything. I thought about creating a "smart group" but I don't see how to send the automated SMS just to new subscribers, not old ones. The scroll bar on the pop-up to select smart groups does not work. Usually with automations, it's new customers added to the flow that get the automated email/coupon, but here I cannot figure out how to automatically send coupon to new subscribers only.