In the app.coolfarmtool.org at the end of the help ? page you can find the API documentation as well as the demo tool to test the endpoints of the connection.
The issuing of the API app key is a benefit of the membership with the CFA. For this, we need a user account that will be linked to the API key. This account has the second key (User API key), visible at the end of the help page, which provides together with app key and the API documentation all you need to set up a connection with the CFT.