If you try to use 619536621, its ID, for the animation, it will fail to load because the asset isn’t truly an animation. It’s a model which contains an animation. You’ll need to insert the asset you linked with InsertService, and you can obtain the animation inside:
No, you can’t paste the ID from the website – it’s a model, and not an animation. You need to insert the ID from the website with InsertService and use the ID of the animation that model contains.
That is the correct ID. In play solo if I paste it into Character > Animate > run > RunAnim and restart the Animate script, I get the zombie run. If you are experiencing issues with the NPC using the incorrect animation, it is due to your script. Can you post what you’re using?