If you are looking to upload a CSV list of customers to Facebook in order to create a custom audience. The minimum requirement is that the CSV file must have an “email” column.
This can be very confusing because the example template that facebook offers have a bunch of unnecessary columns and fields and no mention of what is mandatory and optional.
In summary, as long as you have an email column you are fine to proceed.
If you have any updates since I posted this or have additional comments, please respond in the comments section below.