Ecwid Tokens are used to authenticate requests to your web store from Big Business.
Recently, Ecwid changed the submission process to send Tokens to improve security. This means the old process silently fails and Settings, Test returns, Unable to Connect.
BigBusiness has updated to meet new requirements and you can simply update to fix. Existing tokens can be used with an update to BigBusiness, or get new if you prefer.
Free Trial lets you turn on Ecwid Connect to test with a Free Trial of Ecwid Business.
Presumably, Ecwid still lets you try all features in a free trial including API integration. If purchasing you need their Business Plan to include API and license for Big Business.
To try Ecwid, sign up for a trial, turn on Free Trial in Big Business, and use Automatic settings to bring in new Customers and Orders. Email support@bigbusiness for help.