If you are doing this in the 1040 module, that feature is not available.

Direct the client to pay online https://www.ftb.ca.gov/file/business/types/limited-liability-company/index.html

Actually the $800 should have been paid about the time they filed last year. They should also be paying this years $800.

If they want to mail the payment, they need this form https://www.ftb.ca.gov/forms/2021/2021-3537.pdf