Does SuiteTax work with AvaTax? We installed SuiteTax because our customers were set up in the wrong subsidiary but after turning on the SuiteTax engine we cannot get it to work with AvaTax

It does, but there is a specific bundle for SuiteTax. https://knowledge.avalara.com/bundle/sia1659617841496_sia1659617841496/page/Install_the_AvaTax_bundle_for_NetSuite_SuiteTax.html

AvaTax works good with SuiteTax

Avatax works better with suitetax actually, since they are similar in structure, even suitetax sort of works like an external tax determination engine