Submit the HubSpot form (the one the last form step worked in, else the first visible one) and wait for the page to settle, so the response has a chance to replace the form with its thank-you message or its errors.
Examples
When I submit the form
And I submit the form
When we submit the form
And submit the form
When I submit the form
Pattern
When(/^(I |we )*submit the form$/, …)
Part of @webship-js/hubspot-cms-steps (github.com/webship/hubspot-cms-steps), a step pack for Webship-js 2.0.x.