How to make GIF transparency not turn into white background in After effects?

Question

gif

For a complete understanding - the story in brief:
In After effects, I'm not an advanced user yet; in this case, I introduced gifs into the project for the first time; as planned, the hero and the zombies were supposed to move through the maze. After inserting it into the project window and then into the composition, we see that the gif is on a white background (:-(((sorry azaza). I clicked into Photoshop to remove the white background - to which Photoshop showed that the background is transparent in fact !The background itself is transparent, but the after effects think it is white.How to solve the problem?