Welcome to the community 
As I see from the error message & the console, it seems like the present working directory is a user directory & (obviously) has contents already. You need to create a seperate directory to create and run the app. I would recommend switching to your development space so that it doesn’t lead to clutter.
Once you have opened your command prompt in your dev space, you can run mkdir temp to create a temporary directory and then cd temp to switch to that directory
Once you are inside the newly created directory, you can use fdk create command to create your first app
Also, Powershell/WSL is recommended over command prompt.