If you are using NationBuilder, this article is for you. After providing your subdomain and connecting it to 123FormBuilder, you are prompted to customise the NationBuilder application.
Email opt-in and Mobile opt-in are available when you have a Terms of service field added on the form. Scroll down to your terms of service field and in the Select field dropdown, you can choose from various options. As seen in the below photo, Mobile opt-in and Email opt-in are the first two options.
Here is a list of the most frequently asked questions. For more FAQs, please browse through the FAQs page.