Cloud to Cloud integration using REST API

Hello, I am new to Cayenne. I am interessed by the scenario of connecting Cayenne Cloud API with another Cloud API (REST) that controls devices such as washer, dryer, refrigerator. The goal is to integrate this third-party Cloud API with Cayenne to combine both functionalities.
To test this scenario, I have created an account with Cayenne. I don’t need a raspberry pi to control my washer or my dyer as everything is monitored throw this third-party Cloud REST API, so I didn’t add any device such as raspberry pi or Arduino in my cayenne Dashboard. I am more interested in “Create App” tab. But I have noticed that if I don’t have an appaired device such as raspberry pi or Arduino, there is no APP KEY or APP SECRET.
Do you have any idea about this topic, is it possible to do what I want to do. Does anyone else had this scenario in action?

You have to request it. Here are the docs and a nice project page here

I have already tried this but somehow I get blank and non-editable text box.