Opening the project from the source archive gave me one error message:
Error while saving Prefab: 'Assets/AssetPackages/LeanTween/Examples/Prefabs/EndlessPiece.prefab'. You are trying to save a Prefab with a missing script. This is not allowed.
Please change the script or remove it from the GameObject 'EndlessPiece'.
Since this refers to a sample prefab from the asset I suppose if that isn't actually used anywhere in the game, this will have no real consequences...
Also I got a bunch of warnings, for example
Identifier uniqueness violation: 'Name:spiderweb, Type:Mesh'. Multiple Objects with the same name/type are generated by this Importer. There is no guarantee that subsequent imports of this asset will properly re-link to these targets.
And some component(s) got removed from "Main Camera"...