want transparent background for PIP narrator

I used Adobe Animate (AN) to create a lip-synched dinosaur character who then narrates a video (PIP-LR) that I am making with Premiere Pro (PR).  The mp4 exported from AN has a black background.  I checked the “ignore stage color—generate alpha channel” box in the AN media export dialog and automatically used Adobe Media Encoder to make the mp4.   How do I make the dino narrator background be transparent in the final PR video?  I even tried Adobe Express to make the background transparent in every frame, but downloading that changed video does not make the background transparent in PR.  Thankyou.