Need help with BB data api

Hi all,
I’m on free version and under-development process, so how can I access the data API to examine the data structure response from BB? If you know if there’s any plugin that I can use to meet my goal, that’d be so great?
I go to Settings->API, copy the URL to my APITester but I’ve got this error:
"This application does not expose an API. Please upgrade your Bubble subscription for your API calls to run.

You need to check those boxes for the type you want to expose