This is a frequent question, check the link in the end
We can’t animate tiles in a tilemap yet, but there are two workarounds:
If you want to animate selected tiles from a tilemap you can either create a sprite with a tilesource and put it over a tilemap in place of those tiles and play an animation or using only a tilemap create a script that will change each tile to a next tile in animation sequence in a timer - use tilemap.set_tile.
