Samsung Billing

Hi there, I’m new here as I’ve just purchased my first smartwatch - a gear S3. I’m trying to use Facer but whenever I go into the app it days I need to set up Samsung Billing on my phone. I have set up Samsung Pay and have entered a credit card into my account but the app still tells me to set up billing. I can’t find Samsung Billing anywhere. Can anyone please help? I’d love to start using this app.
Thanks in advance

I have exactly the same problem. I have an Android phone on 7.0 and a Gear S3.
I can’t change watch faces due to requiring Samsung Billing which I can’t find.