I have the newest version of the assets that's available for download - it says on the download page that the last update was 74 days ago:
And I bought it fewer days ago than that, so in theory I should be on the latest version of the asset pack, unless that download isn't up-to-date, right?
As for engine, I'm building in unity tilemaps. Out of curiosity, in RPG maker, could it be rotating the top-inside corner pieces to make bottom inside corner pieces? If so, I'm not aware of unity having the same feature.