Unreal Engine & After Effects Render Error?

Hey guys, i am very new at this ,trying to do some 3D tracking & placement.

Step 1 . I have found how to do the simple workflow , but when i render my shots, it gives out a BLACK BACKGROUND , i changed the alpha settings, that i found out about in a tutorial. ( in the project render settings ).

Step 2 . when i import to After Effects , the model from unreal , it gives me a fully BLACK background
( should be transparent ?? ) .

Here i uploaded a video of settings and the after effects problem & my render settings.
thank you very much

I know people here are high level, but i don’t know what else to do, since i have seen tutorials, but nothing works to give me a transparent background.

Thank you all .

https://www.youtube.com/watch?v=FMbsY4ivDuI