A ministry selling a physical book needs a shipping quote and a tax figure at checkout. Both come from outside services, keyed per ministry, so each one bills for its own postage.
Open the tenant’s Vendors panel.
Set the shipping key.
The panel then lists the carriers that key actually unlocks.
Set the tax key.
Watch out
A shipping quote depends on the address being right as well as the key. A state typed as a name where a code was wanted has broken checkout before, and it looks like a vendor outage rather than bad data.