could not run legacy post zone sub request against new zone products: failed to update user subscription: failed to apply object products: You cannot add or modify subscriptions or services until the outstanding balance is paid. You should be able to do so in your Billing page.
If you already have a ticket, Support will respond to you on that ticket.
You’ll need to follow these directions here, Billing, Plans & Subscription Questions. The Community cannot assist with Billing, Account nor Registrar issues, you need a ticket with Support.