Connecting BigCommerce shows the exact steps and permissions

Connecting a BigCommerce store used to offer a bare link to BigCommerce and no steps, so the API permissions were a guess, and a wrong guess ended in an access error you couldn't read. The connection screen now walks you through creating the API account, lists the exact permissions to tick, and says what to copy where. The Shopify steps were updated too, so they match the screens Shopify shows today. Connecting is described in Accounts and regions.