The Essential plan from Nationwide Mutual Insurance is for travelers planning trips on a budget who don't want to sacrifice coverage. Coverages include Trip Cancellation and Interruption, Medical, Emergency Medical Evacuation, and Assistance Services.
To learn more, see the Nationwide Essential trip insurance product page.
InsureMyTrip emails a Confirmation of Coverage which is your Nationwide policy. Based on your review, it appears that you printed the confirmation email and took it with you on the trip. The confirmation email is exactly what you needed to bring since it has the policy number and provider contact information along with an attached copy of the Nationwide Certificate of Insurance.