Firstly, you need to raise a ticket with our Support Desk here. Simply request for a new API token to be created on a specific storefront of yours and we will then provide this for you.
Our API uses basic authentication, so when using Postman to test the API you can take the API Token and add it to the Authorization tab, with Type set to Basic Auth. Then paste the API Token into the Username field.
To test this out, download the attached Postman Collection which includes our Authentication check API Request.
The response contains details about the storefront and provides confirmation that the API connection is good.