I have an error.

[Tigitaal]

Library\PackageCache\com.unity.2d.tilemap.extras@dcb0c48\Runtime\Tiles\AnimatedTile\AnimatedTile.cs(171,26): error CS1061: 'ReorderableList' does not contain a definition for 'IsSelected' and no accessible extension method 'IsSelected' accepting a first argument of type 'ReorderableList' could be found (are you missing a using directive or an assembly reference?)

[ChuanXin-Unity]

Hi, if you are using the 2020.3 Editor, please use the 2020.3 branch found at https://github.com/Unity-Technologies/2d-extras/tree/2020.3 instead of the master branch.

You can do this from the following steps:
Window > Package Manager > Add package from git URL... > https://github.com/Unity-Technologies/2d-extras.git#2020.3

Hope that helps!