For Alpha, you’ll need to go to ProRes4444
But, You don’t need Alpha.
Export your clips on green “Current Settings”
Drop them in AE, key out green ~ drop in backgrounds.(minus Text)
Render out ProRes to match your sequence.
You could add the Text parts in FCP, after you have your keyed clips back from AE.
Make Sense?
Chris Tompkins
Video Atlanta LLC