I have contacted Taxamo Assure and they have been hopelessly unhelpful!
They keep fobbing us off with links to ‘guides’ but cannot give any specific information about how to integrate with Shopify - it feels like Royal Mail have recommended them without actually checking that they can deliver the service/solution.
It would be AMAZING if the Shopify technical team could simplify this and help their users integrate Taxamo Assure - ultimately having this integrated will ensure sales to Europe don’t drop!