Hi WinLu, I am using Unity, and there is a package called "Autotile Importer for RPG Maker-Compatible Tilesets image" from Unity assets shop can simply turn your RPGMarker version assets into autotiles.
here is the link
https://assetstore.unity.com/packages/tools/sprite-management/autotile-importer-...
There is a little issue in unity tho, handling the shadow is not easy (even we use photoshop to edit it, it still looks questionable) in Unity. It could be way better if we can have an autotile version of shadow