Glad to hear everything works ok. Customers are not automatically added to your email list - they are sent an opt-in email where they can choose to be added to your list, so it may just be that they chose not to.
You can check it’s working by downloading a beat from yourself using an email address that’s not associated with your list in any way (e.g. it isn’t the email address you signed up with, and hasn’t already been added to the list). Then when you receive the opt in email, opt in and you should be added
(mail.com has a very quick and easy signup process if you want to create a new email address to test this with)