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.
Questions about billing will need to be resolved by the Customer Support team and cannot be resolved on the Community.
To contact the billing team, please submit a new support request from your Cloudflare account directly through the Cloudflare dashboard. Visit https://dash.cloudflare.com/?to=/:account/support and choose Billing. Please share your ticket number here so that we can track it.