Square is the payment / POS company making commerce easy and accessible to everyone. This module integrates their Connect APIs for online payments and inventory into Drupal Commerce 2.x.
Review Square APIs: Getting Started to get your Square account, application, and sandbox access configured.
This module provides a Drupal Commerce payment gateway that integrates with Square Payment Form. This allows you to collect payment using your Square account online.
See Testing using the API sandbox to test the integration.
Remember: Your Personal Access Token is for OAuth integrations (currently not implemented.)
In order to test the Square Payment Form you must use the Sandbox Application ID and Sandbox Access Token provided in your application.