You may want to read this thread.
I'm not sure why you need to go through the interface. Perhaps you want to use a software "cable" so Wirecast sees Logic as a source.
You may want to describe what you're trying to do.
There are two ways to get Logic Pro into Wirecast.
INTERNALLY GENERATED AUDIO
If you are using computer generated sound, you can either
- System Audio Capture. While this works, it will get ALL system audio. I personally avoid this, to avoid audio loops etc.
- Use Dante VIA or equivalent. This will create a virtual interface on your PC that you will send Logic output to... and you will then route it to a virtual sound card input to Wirecast. This is a better option to route computer generated audio, because no external cables are required. It is all internal high quality audio.
EXTERNALLY GENERATED AUDIO
If you are sending Logic audio to an externally midi connected device, your Focusrite Scarlet should work fairly easily. You say a mic input to it works? One check would be to get some headphones on the Focusrite and confirm the audio path into it is working as expected. Don't forget, the Focusrite will probably be a multi-channel input. Check the Chanel map for your input device. Your first port could theoretically be a stereo input port on channels 1 and 2, and the 2nd port could be channels 3 and 4. Going into the channel mapper will help you confirm.
I hope that helps.