I ended up using the built in Ultra Key Effect (green screen) that comes with Premiere. Lots of tutorials on how to use this. Make sure you add a solid color behind your animation and don't leave the default grey or won't work.

I have tried to export Popvideo and re-load in CTA, it does work have the transparent background. You can refer method.

Good to know thanks! I'll try that on my next project...

Under SCENE> SKY

turn off visibility... the eye