How to Create a Subscriber List of WordPress Users
To create a Meta list based on User Meta stored in the database follow these steps.
1. Create a New List. Subscribers > Lists
2. Choose a Subscriber Role
3. Uncheck "Allow User to Sign up to this list"
4a: Select the WordPress Role, ie Subscriber. Remember to sync the list manually before sending a newsletter.
4b. If you want to query the Database to create a lit using information stored there, select User Meta Query.
Keep in mind the Meta Query is a very advanced list type that requires significant understanding as to how to find data in your User Table.