The API Docs page explicitly states:
Disclaimer - Any use of the API should be tested in AtTask's beta environment prior to being run in the production environment.
I have not been able to find exactly where to access the beta nor other information like authenticating with beta.
Does anyone know how to beta test the api?
Your test environment(s) is shown inside workfront. Click setup on the top bar (correct permissions required)
Select preferences on the side bar:
Your test environments will be listed at the bottom of the page: