If the Swagger document was entered and deployed through Menu > API Management > API Detail Screen, the Swagger document of the most recently deployed version will be displayed.
The API Document detail screen shows the Swagger UI as shown in the image below.
You can use the [Authorize] button in the Swagger UI to set the API KEY and perform API testing. (Refer to API KEY creation/management for more details)
API testing can be done by clicking the [Try it out] > [Execute] buttons for each specific API in the Swagger document.